Add PlayerRepository to media module

[luizgrp]

WHAT

Add PlayerRepository and domain models to media module.

WHY

In order to have a PlayerRepository that is independent of Media3 dependencies.

Checklist 📋

• Add explicit visibility modifier and explicit return types for public declarations
• Run spotless check
• Run tests
• Update metalava's signature text files

[yschimke]

Nothing blocking and probably easier to have the next batch of discussions on incremental PRs.

[dpreussler]

what is a media item that has neither title nor artist. Is this sth we want to support?

[luizgrp]

@yschimke please see the above, I ported this way to follow the implementation in the media toolkit, was there any use case for that in mind?

[luizgrp]

@dpreussler what would be your suggestion?

a) non-nullable title?
b) non-nullable title and artist?
c) keep both them nullable but enforce clients to provide one or the other via factory methods?

please let me know if you have a different idea in mind

[yschimke]

If we think in 95% of apps using this code we should avoid the hassle of nullability and require them. Maybe just a note that empty "", should be used if there legitimately isn't one.

There can be multiple artists (track artist, album artist) perhaps we should make this clear it's whatever we want for display? displayArtist. But I don't know, so happy to go with non nullable artist for now.

[luizgrp]

made the changes re non nullable artist

good point re display artist, will land it as it is and we can evolve it from there as this require further discussion