Support for opensubsonic extension api for transcoding decisions in subsonic implementation.
This change deprecates the BNB_SUBSONIC_CUSTOM_CLIENTS config, so remove that.
Important: When using this approach, ensure the bonob player in your Subsonic server has no Transcoding profile assigned and no Max Bit Rate cap. A server-side player override would replace bonob's capability profile and prevent the extension from working correctly.
thanks to @AliceGrey