Allow for a seperate catalog & music extension

[MixSens]

Summary

Allow to designate an extension for catalog and another for music playback

The Problem

The Ideal Solution

Catalog extension could be one which only provides home feed, playlists etc.
music playback extension could be one which only fetches requested song

eg: designating Spotify as catalog extension and DabMusic as music playback extension.

That way, Spotify extension allows for using Spotify's home feed, extensive curated playlists etc. and when requested to play a song, DabMusic provides with the song to play instead of Spotify extension.

Spotify - provides home feed, playlists
DabMusic - provides required song

This allows for leveraging the benefits of both Spotify (curated playlists, nice home feed) and DabMusic (hi-res audio)

The Current Solution

Checklist

• I have searched the open AND closed issues for any duplicates.
• If this is an issue with an extension, I should be opening an issue in the extension's repository.

Additional Context

[github-actions]

If this is an issue with an extension, please open an issue in the extension's repository.

[brahmkshatriya]

Rather than that, I have thinking of adding support for opening streams from other extensions,
maybe something like, a "search for this track on other extension" thingy, which could automatically select the best same looking song.

[MixSens]

That would be great! but in case of Android Auto where one can't interact with the phone much. An option in settings to pre-define the default extension for each category sounds better.

Or to reduce overall settings clutter, this feature could only be allowed while using the Unified Extension and setting required values in extension settings.