Add TileAdapterDelegate

Use an AccessibilityDelegate for the actions in QSCustomizer. Adding or
removing a tile can now be done with the click action, whereas moving or
adding to a particular position require a context action.

This removes the old custom dialog and improves the overall
accessibility.

Test: manual
Test: atest TileAdapterDelegate
Bug: 168039987
Bug: 140366995

Change-Id: Ib5b19aeebb54c46573555563c3f39bd922b68896