floss: Add support for BlueZ - Floss device migration

Migrate existing device information between BlueZ and Floss on each
transition between the two so users have a seamless experience
during the transition period to Floss.

Bug: 233111678
Bug: 233111981
Tag: #floss
Test: Confirmed devices are synced between each transition
Change-Id: Ic3670c914b0fb4169e0a987e8ddb49357ccea0b6