Do not synchronize tile state callbacks

Instead, use a CopyOnWriteArray to hold callbacks.
This saves a few milliseconds, which saves a frame being dropped when
expanding the shade.

Flag: com.android.systemui.qs_new_tiles
Bug: 343622531
Test: atest QSTileViewModelAdapterTest
Change-Id: I5b3e635717549bb1078450457688736a5d33aba2