[TIMOB-17358]: Refactor notification, add new features, update appcompat +...

... scons

This pull request contains pre-release data. Please do not merge.

This PR contains the following changes:

- Update scons to build with Android-L
- Update appcompat libraries and assets to run with Android-L
- Update android projects to run with Android-L
- Refactor Notification
- Implement category, priority, visibility properties for notification