Setting up environment for media control view-binder

Adds seek bar view model work, and modify some fields in view-models.

Flag: ACONFIG media_controls_refactor DISABLED
Bug: 328207006
Test: atest SystemUiRoboTests:MediaControlViewModelTest
Test: build.
Change-Id: I62e5caee4958b1f27c5a0337c53aea4f691e4f16