leaudio: Provide audio sessions to codec manager

Codec Manager needs to be feed with the unicast and broadcast sessions.
This is preparation for the Codec Extentions usage.

Bug: 340400131
Bug: 313054645
Test: atest bluetooth_le_audio_client_test bluetooth_test_broadcaster bluetooth_le_audio_codec_manager_test
Change-Id: Ibdb348175b85c6464f8131dcb6d8065a9a4e8bfd