Add root small screen capture record view model.

This will be a root view model for the screen recording on a small screen. It will orchestrate the bottom floating window state and start/stop the recording.

Flag: com.android.systemui.new_screen_record_toolbar
Test: passes presubmits
Bug: 428686600
Change-Id: Id26db1160442541180a415a39fca871f71f8cef2