le_audio: Move set configurations

This moves the set configurations out of the
le_audio_types.h, and hides them behind the set configuration
provider.

This abstraction will allow for the next step, which is moving
from the hard-codded configurations to loading them from the
external sources, eg. XML/JSON files.

Bug: 150670922
Tag: #feature
Sponsor: jpawlowski@
Test: atest --host bluetooth_le_audio_test
Change-Id: I6435f6259d4d098da8c298a358c2b41dfc38ac10