LeAudio: Remove the redundant set_configurations namespace

There is no need for separate bluetooth::le_audio::types and
bluetooth::le_audio::set_configurations name space, as there are no
clear definition of each namespace and their purpose. Some data structures
from one namespace are reused or nested into the other namespace. To reduce
the complexity, confusion and the hussle when reusing these symbols, lets
simply put them both into the bluetooth:le_audio::types namespace.

Bug: 388733112
Test: atest --host bluetooth-test-audio-hal-le-audio-software bluetooth-test-audio-hal-aidl-leaudio-utils bluetooth_le_audio_test bluetooth_le_audio_client_test  bluetooth_test_broadcaster bluetooth_test_broadcaster_state_machine bluetooth_le_audio_codec_manager_test net_test_btif net_test_btif_hh net_test_btif_stack
Flag: EXEMPT; mechanical refactor
Change-Id: I8dddbdedc6fcd9919e67553c7afc05d53f6106e7