MediaControlView2: Add Minor UX fixes

This CL adds the following changes:

1) Support for Mute/Unmute button
2) Make SeekBar entirely buffered for local files
3) Update Subtitle and VideoQuality buttons to have an equal size.

Bug: 73094639
Test: Run VideoViewTest.apk
Change-Id: I1d21fe62e8ba93e3f258c8afefdcc109a1ea679a