Add a listenbrainz submission plugin

[amCap1712]

Based on the last.fm plugin, add a plugin to submit listens to ListenBrainz. The API format for ListenBrainz is documented at https://listenbrainz.readthedocs.io/en/latest/users/json.html.

FWIW, I am a maintainer of the ListenBrainz project. Also, I am not very well-versed in C development, especially have never used dispatchlib before so I copied the code relevant code verbatim from the lastfm plugin as needed.

Fixes #2085

[Oleksiy-Yakovenko]

Hello @amCap1712 ,
Is there any reason why you'd want to submit this plugin upstream?
It's not common to do this in Deadbeef, instead we provide a convenient way to build and distribute 3rd party plugins for their respective developers.
This has the benefit of being able to update plugins more frequently than deadbeef itself,
and plugin developers can do whatever they want with the code without pull requests.
We do make exceptions for critical plugins (like pipewire), but there has to be a very good reason.

[amCap1712]

Hi @Oleksiy-Yakovenko, I wasn't aware that submitting plugins upstream isn't the norm in Deadbeef. Some avid deadbeef users have asked for it in the past on the linked issue and in our project channels. The last.fm plugin existed upstream. And in general I think more people would use it if it was available out of the box. Hence, I decided to submit it here.

FWIW, plenty of other music players like funkwhale, strawberry, mpd, rhythmbox etc. offer ListenBrainz's plugins out of the box now.

[Oleksiy-Yakovenko]

FWIW, plenty of other music players like funkwhale, strawberry, mpd, rhythmbox etc. offer ListenBrainz's plugins out of the box now.

I don't know whether any of those players support plugins, but the whole point of plugins is that they are add-ons, and they don't need to be part of the main app.

[Oleksiy-Yakovenko]

I can offer an acceptable (for me) alternative to include this functionality in upstream sources:

We can add ListenBrainz integration to the existing lastfm plugin and implement "multi-scrobbling".
i.e. submit plays to multiple endpoints
have 2 checkboxes and 2 username/password fields in the plugin preferences
(although this can get pretty messy)

This would prevent code duplication and ensure that both scrobblers work identically, and benefit from the same code improvements.