Fix ButtonItem theme in appcompat

Inflate the button from XML rather than calling the constructor
directly, so that AppCompatActivity can use the injected layout
inflater to tint the button drawables.

- Migrated existing ButtonItemTest to robolectric
- Added new ButtonItemDrawingTest as instrumentation test to test
  the drawing behavior. Created DrawingTestHelper and
  DrawingTestActivity to help in testing draw behaviors in normal and
  AppCompat contexts.

Bug: 35325693
Test: ./gradlew connectedAndroidTest
Change-Id: Ic2215f5510c246a861ab109e3dffee49f9cf9b3c