VideoView: Change showSubtitle() to get boolean parameter

- Adds VideoView2 attributes
  - enableControlView
  - showSubtitle (boolean)
  - viewType (enum)
      - surfaceView
      - textureView

- showSubtitle() --> showSubtitle(boolean)
- hideSubtitle() removed.

Test: build

Change-Id: Ib21722af1c9c1caf036e047a18d27d46097e8f03