[TEMPURA-2186] Custom icons support

[pablo-skyscanner]

This PR enables support for adding custom icons without requiring them to be added to the Backpack library.

• Check this if you have read and followed the contributing guidelines

Remember to include the following changes:

• README.md
• Tests
• Screenshotting code
• Adding a component? Remember to expose it in the main Backpack.h header file

If you are curious about how we review, please read through the code review guidelines

[github-actions]

Snapshots were updated. Please verify the changes match the expected layout.

' D Backpack-SwiftUI/Tests/BannerAlert/Snapshots/BPKBannerAlertTests/test_multilineBannerAlert.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/BannerAlert/Snapshots/BPKBannerAlertTests/test_multilineBannerAlert.light-mode.png'%0A' D Backpack-SwiftUI/Tests/BannerAlert/Snapshots/BPKBannerAlertTests/test_multilineBannerAlert.rtl.png'%0A' D Backpack-SwiftUI/Tests/NavigationTabGroup/Snapshots/BPKNavigationTabGroupTests/test_dark.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/NavigationTabGroup/Snapshots/BPKNavigationTabGroupTests/test_dark.light-mode.png'%0A' D Backpack-SwiftUI/Tests/NavigationTabGroup/Snapshots/BPKNavigationTabGroupTests/test_dark.rtl.png'%0A' D Backpack-SwiftUI/Tests/NavigationTabGroup/Snapshots/BPKNavigationTabGroupTests/test_default.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/NavigationTabGroup/Snapshots/BPKNavigationTabGroupTests/test_default.light-mode.png'%0A' D Backpack-SwiftUI/Tests/NavigationTabGroup/Snapshots/BPKNavigationTabGroupTests/test_default.rtl.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_clearableField_withPrefixIcon.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_clearableField_withPrefixIcon.light-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_clearableField_withPrefixIcon.rtl.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_disabledField_withCustomPrefixText.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_disabledField_withCustomPrefixText.light-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_disabledField_withCustomPrefixText.rtl.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_disabledField_withPrefixIcon.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_disabledField_withPrefixIcon.light-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_disabledField_withPrefixIcon.rtl.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_errorField_withCustomPrefixText.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_errorField_withCustomPrefixText.light-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_errorField_withCustomPrefixText.rtl.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_errorField_withPrefixIcon.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_errorField_withPrefixIcon.light-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_errorField_withPrefixIcon.rtl.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_validField_withCustomPrefixText.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_validField_withCustomPrefixText.light-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_validField_withCustomPrefixText.rtl.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_validField_withPrefixIcon.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_validField_withPrefixIcon.light-mode.png'%0A' D Backpack-SwiftUI/Tests/SearchInputSummary/Snapshots/BPKSearchInputSummaryTests/test_validField_withPrefixIcon.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_clearableField_withCustomPrefixText.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_clearableField_withCustomPrefixText.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_clearableField_withCustomPrefixText.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_clearableField_withPrefixIcon.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_clearableField_withPrefixIcon.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_clearableField_withPrefixIcon.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_defaultSettings_withCustomPrefixText.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_defaultSettings_withCustomPrefixText.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_defaultSettings_withCustomPrefixText.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_defaultSettings_withPrefixIcon.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_defaultSettings_withPrefixIcon.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_defaultSettings_withPrefixIcon.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_disabledField_withCustomPrefixText.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_disabledField_withCustomPrefixText.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_disabledField_withCustomPrefixText.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_disabledField_withPrefixIcon.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_disabledField_withPrefixIcon.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_disabledField_withPrefixIcon.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_emptyField_withCustomPrefixText.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_emptyField_withCustomPrefixText.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_emptyField_withCustomPrefixText.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_emptyField_withPrefixIcon.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_emptyField_withPrefixIcon.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_emptyField_withPrefixIcon.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_errorField_withCustomPrefixText.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_errorField_withCustomPrefixText.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_errorField_withCustomPrefixText.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_errorField_withPrefixIcon.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_errorField_withPrefixIcon.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_errorField_withPrefixIcon.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_validField_withCustomPrefixText.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_validField_withCustomPrefixText.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_validField_withCustomPrefixText.rtl.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_validField_withPrefixIcon.dark-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_validField_withPrefixIcon.light-mode.png'%0A' D Backpack-SwiftUI/Tests/TextField/Snapshots/BPKTextFieldTests/test_validField_withPrefixIcon.rtl.png'%0A' M Example/Backpack.xcodeproj/project.pbxproj'%0A'?? Backpack-SwiftUI/Tests/Icons/Snapshots/BPKIconViewTests/testCustomLargeIcon.dark-mode.png'%0A'?? Backpack-SwiftUI/Tests/Icons/Snapshots/BPKIconViewTests/testCustomLargeIcon.light-mode.png'%0A'?? Backpack-SwiftUI/Tests/Icons/Snapshots/BPKIconViewTests/testCustomLargeIcon.rtl.png'%0A'?? Backpack-SwiftUI/Tests/Icons/Snapshots/BPKIconViewTests/testCustomSmallIcon.dark-mode.png'%0A'?? Backpack-SwiftUI/Tests/Icons/Snapshots/BPKIconViewTests/testCustomSmallIcon.light-mode.png'%0A'?? Backpack-SwiftUI/Tests/Icons/Snapshots/BPKIconViewTests/testCustomSmallIcon.rtl.png'

[frugoman]

Looking good and clean!! Thanks for this! it will be quite useful!