Add a TileSpecRepository

This tracks and modifies Settings.Secure.QS_TILES.

Also add a PrototypeCoreStartable to hook up parts of the pipeline in progress for testing.

Flag: QS_PIPELINE_NEW_HOST
Test: atest TileSpecSettingsRepositoryTest
Test: manual see logs
Test: adb shell cmd statusbar qs-pipeline
Fixes: 274108007
Change-Id: Ia6b5cd0627040d9833a1ec56c51ad445c192f8b5