bluetooth: Refactor BT Audio Codec list

* Show only selectable codecs to the user
* Removed redundant 'abstract' layer
* Disable codec selection when BluetoothA2dp, active device unavailable
  or HD Audio disabled.

Bug: 329809288
Bug: 346490998
Flag: EXEMPT - refactor
Test: atest SettingsRoboTests:com.android.settings.development.bluetooth.BluetoothCodecListPreferenceControllerTest
Merged-In: I56ebfeaf2cfa22ec253db897d7b7e96d1f8eee61
Change-Id: I23714715d9257479f5eac1a172ba1804da7e64e3