If the sink device has connected the broadcast source, then the device
should initialize the sourceId and create the sourceId's preference UI.
Bug: 231576575
Test: manually test
Change-Id: I24d9e6d4c78dc4e583c5253e552456a68b1114c3
Add function for 'leave broadcast' button
Add function for 'Scan QR code' button
Set 'level broadcast' button gray out when device does not have broadcast source
Bug: 228259065
Test: build pass and manually test
Change-Id: Iab4a45e73f49c3f755b95ea3fa38872daac7e745