This commit refactors queue management and transport control to use a unified approach across all renderer backends (UPnP, OpenHome, Arylic TCP, Chromecast, LinkPlay). Key changes include:
1. Introduces `RendererBackend` and `QueueTransportControl` traits to provide consistent queue access and transport control operations
2. Moves queue management from the `MusicRenderer` struct to individual backend implementations
3. Implements `play_from_queue`, `play_next`, `play_previous`, and `play_from_index` methods in all backends
4. Simplifies `MusicRenderer` methods to delegate to backend-specific implementations
5. Removes direct queue access methods from `MusicRenderer` and centralizes queue operations in backend traits
6. Updates all backend implementations (UPnP, OpenHome, Arylic TCP, Chromecast, LinkPlay) to implement the new queue transport control traits
This change provides a more consistent and maintainable way to handle queue operations across different renderer types, ensuring that queue management and playback navigation work uniformly regardless of the underlying backend.
Eric Coissac
c3a9e3ea7b