Add TaskbarModeSwitchRule to test both transient/persistent taskbar.

- Lays the foundation for transient taskbar tests.
- Does not add flags that would add ACTION_OUTSIDE in tests.
  We can address testing this functionality in a separate CL

Bug: 257549303
Test: TaplTestsTaskbar
Change-Id: I44acc5e589b959e6d4bc93fdc369e503c54e7d87