LE Audio: Broadcast Assistant should discover PACS

[Thalley]

Is your enhancement proposal related to a problem? Please describe.
A BAP broadcast assistant should discover PACS on the Broadcast Sink/Scan Delegator device to determine if it supports a broadcast source. Currently this isn't possible with the API.

Describe the solution you'd like
Similar to how the bt_bap_unicast_client_discover discover PACS, the bt_bap_broadcast_assistant should also discover PACS on the remote device.

Describe alternatives you've considered
N/A

Additional context
N/A

[jthm-ot]

I can take it

[Chris-StJohn-Bose]

@jthm-ot @Thalley please be aware that there are proposals to extend PACS in the near future. I'm running IOP with a modified version of pacs.c and bap_unicast_client.c. It would be nice if your refactor could make extending PACS a little easier.

[Thalley]

@jthm-ot Any plans for this in the near future?
Since this will likely conflict with #70826 I'm like to have at least 1 of the 2 implemented in the near future