LeAudio: Configuration provider dependency inversion - Part 3

Part 3: Moving the Unicast audio configuration provider API

This change moves the Unicast audio stream configuration provider
behind the Codec Manager API so that the unicast audio code would
not care where the codec is being located.

Bug: 308428860
Bug: 295972694
Test: atest --host bluetooth_le_audio_test bluetooth_le_audio_client_test bluetooth_test_broadcaster bluetooth_test_broadcaster_state_machine bluetooth_le_audio_codec_manager_test
Flag: EXEMPT; refactor for the multicodec support - verified with unit tests and manual testing
Change-Id: Ia756c241612cb330935da218f4450440b54685bd