[hackerone][iOS] Fix Reader Mode

[stoletheminerals]

See https://hackerone.com/reports/2760854

[kjozwiak]

The above requires 1.71.117 or higher for 1.71.x verification. Going to leave this as a single check rather than QA/Test-All-Platforms as we'll run through the reader mode when we're running through the manual passes for 1.71.x.

[Uni-verse]

Verified on iPhone 12 running iOS 18 using version 1.71.118

• Ensured that reader mode icon is shown in the URL bar for articles.
• Ensured reader mode works with Top Bar and Bottom Bar configurations and as well as with light/dark modes.
• Ensured enabling reader mode works on different different articles and there are no issues toggling reader mode.
• Ensured that reader mode settings are retained when reader mode when switching from different webpages.
• Ensured that reader mode will continue to be used after restarting brave.

example	example	example	example