Add fitsSystemWindows for edge-to-edge support

[cmaier]

Improve edge-to-edge support for apps targeting Android API level 35 by adding android:fitsSystemWindows="true" to the layouts used in activities.

How to test?

• Integrate this branch in our latest App project
• Start Scan&Go and test e.g. this:
  • adding a credit card should not be in bounds
  • the checkout process should now be in bounds

Definition of Done

• Issue is linked
• All requirements of the issue are fulfilled
• Changelog is updated
• Documentation is updated
• Self-Review
• Review with the Product Owner (Release-Variante o. Minified Build)

App Tests

• Minified build has been tested (aka. Release Build)
• Environments have been taken care of (Production/Staging)
• Supported languages have been tested
• Light-/Dark-Mode has been tested
• Edge-Cases have been tested
• Android API Levels have been taken care of (minSdk?)

Testing

• Tests have been written (aka Unit-Tests, Integration-Tests, ...)