Add a CurrentTilesInteractor

This will be the layer that will interact with UI (like QSPanel,
QSCustomizer) as well as API (CommandQueue) to retrieve and modify the
list of current tiles. For now it exposes state methods for interop with
Java.

When the flag is off, it won't collect changes in the repository
(to prevent tiles being created twice). QSTileHost will be used.
When the flag is on, QSTileHost won't react to changes, and
CurrentTilesInteractor will be used to track the tiles.

Also, provide a QSHostAdapter that switches between QSTileHost and
CurrentTilesInteractor so the new behavior can be observed without
having to change consumers.

Flag: QS_PIPELINE_NEW_HOST
Test: atest com.android.systemui.qs
Test: atest android.host.systemui CtsTileServiceTestCases
Test: manual, enable flag and observe no difference
Fixes: 275597752

Change-Id: I3bafe78c7f191faca1a9dd6e7e9d22c88c70926f