Consolidate visibility and window LayoutParams

Removed isAttached, now that we don't need to have the window in the
hierarchy when the UI is not visible.

Also hooked up touch spying to the UI expansion state, correctly
handling the dismissal of the pill, which triggers removal of the window.

Bug: 403422950
Fixes: 415913098
Test: atest AmbientCueRepositoryTest AmbientCueInteractorTest
Flag: com.android.systemui.enable_underlay
Change-Id: I8cce42b6cbaf8b3f6c7c5486e687d4e83a4e3457