KOA-4949 Update FloatingPanel from 1.6.6 to 2.5.2

[gert-janvercauteren]

Update the floating panel layout to the latest release (2.5.2)

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

Remember to include the following changes:

• UNRELEASED.md
• README.md
• Tests
• Screenshotting code
• Adding a component? Remember to expose it in the main Backpack.h header file
• Docs (either update backpack-docs now, or create a follow up ticket)

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[frugoman]

Looks pretty good, just super small comments/questions.
dont forget the UNRELEASED file