shared/bap: Add support for BAP broadcast sink

shared/bap: Add support for BAP broadcast sink

This adds support for BAP broadcast sink, creates a remote endpoint when a
broadcast source is discovered and synchronizes with the source upon
endpoint configuration.
This feature was tested using bluetoothctl with the following commands:

[bluetooth]# endpoint.register 00001851-0000-1000-8000-00805f9b34fb 0x06
[bluetooth]# scan on
[NEW] Endpoint /org/bluez/hci0/dev_XX_XX_XX_XX_XX_XX/pac_bcast0
[bluetooth]# endpoint.config
/org/bluez/hci0/dev_XX_XX_XX_XX_XX_XX/pac_bcast0
/local/endpoint/ep0 16_2_1