Create DragZoneFactory for bubble drag zones

Creates a factory for bubble drag zones. This currently only supports
dragging bubble objects, but may be extended for dragging other
objects, e.g. launcher icon, into bubble drag zones.

This initially only handles dragging bubble icons and the bubble bar.

Flag: EXEMPT not wired
Bug: 393172431
Test: atest DragZoneFactoryTest
Change-Id: I15b4b97f6bc6809e20611b2b7333bde54c86c831