Isolate shell dependencies

- Add initializer path for required shell dependencies
- Move shell dependencies into WMComponent scope, and expose shell
  features to SysUIComponent explicitly
- Moved temporary Bubble's specific dependencies to global scope until
  the migration finishes

Bug: 162923491
Test: atest WMShellUnitTestsWMShellUnitTests
Test: make SystemUIGoogle CarSystemUI ArcSystemUI AAECarSystemUI
Test: Verify pip/split/onehanded/bubbles still works

Change-Id: Ibaa8b5a718f32a1fff49d1756a18a009d6ad164f
Signed-off-by: Winson Chung <winsonc@google.com>