Add guts to media player on long press

Adds the following:
* Button for accessing settings
* Button for dismissing player (similar path to when a package is
uninstalled)

Guts will close automatically if:
* QS is collapsed
* Media carousel changes pages

Also, flattened the view hierarchy to support animations between states.

Test: manual
Test: atest com.android.systemui.media
Bug: 156036025
Change-Id: I340e0b37393573f81a3bf12d5e453eccf5982473