Handle bluetooth callback and toggle switch, also moved `getDeviceItems` to background thread.

The dialog opens first with empty device list, then the list updates after `getDeviceItems` finishes.

Flag: BLUETOOTH_QS_TILE_DIALOG
Test: atest -c BluetoothTileDialogTest BluetoothTileDialogViewModelTest DeviceItemFactoryTest DeviceItemInteractorTest BluetoothTileDialogRepositoryTest BluetoothStateInteractorTest
Bug: b/298124674 b/299400510
Change-Id: Ib7d4ab9773b7741caf474a273c45d9568eb52566