Merge android-notification-channel-groups into develop

[thomasgalliker]

Description

Create and delete notification channel groups. Assign groups to notification channels.

Issues

• 56

Checklist

• [x] General
  • The modified code fulfills the intended purpose and functions correctly.
  • Existing code continues to function without errors.
  • Performance has not been significantly impacted.
  • All TODOs in the code have been removed and, if necessary, recorded as follow-up tasks in Remine.
• [x] Testing
  • All existing unit tests pass successfully.
  • New functionalities are covered with unit tests.
  • Code coverage through unit tests has been verified.
  • Exploratory tests on real devices have been conducted on both platforms (iOS and Android).
• [x] Readability
  • Code style has been applied according to .editorconfig.
  • Naming conventions for variables and methods are clear and consistent.
• [x] Documentation
  • In-code comments are meaningful or replaced by self-explanatory code.
  • Changes to interfaces are documented in readme.md.
  • Updated the release notes under <PackageReleaseNotes>.
• [x] Security and Data Protection
  • Sensitive data is not unintentionally logged or stored.
  • User inputs have been validated.