broadcaster: Confirm stream resume after BIG create

While a broadcast stream uses the Audio Framework (AF), the confirmation
should be sent as soon as the Broadcast Isochronous Group (BIG) is created.
This lets the offloader know the connection handles of the Broadcast
Isochronous Streams (BISes).

Bug: 378564463
Bug: 347204335
Flag: com.android.bluetooth.flags.leaudio_big_depends_on_audio_state
Test: atest bluetooth_test_broadcaster
Change-Id: Ie53e2be85d6e504194188875fcc226aaf6f6f490