Migration to AndroidX
- Update to API level 29
- Update Java sourcecode and xml import statements
- Upgrade Butterknife Version 10 AndroidX support
- Set Java 8 compile options due Butterknife needs it
* BaseMediaActivity enforces a common layout which allows us to more
easily add new common UI elements
* All activities that allow browsing media should extend BaseMediaActivity
Currently CastActivity is the only exception.