feat: add a submission_client to ListenBrainz scrobbles

[Kernald]

Please check existing knowledge before opening an issue

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Describe the new functionality

As per https://listenbrainz.readthedocs.io/en/latest/users/json.html#payload-json-details:

The name of the client that is being used to submit listens to ListenBrainz. If the media player has the ability to submit listens built-in then this value may be the same as media_player. Don’t include a version number here.

Adding media_player would be nice as well, if we can get it - but this isn't as simple as passing the client (e.g. Plex could be web UI, Plexamp...)

Configuration Example

No response

Will you help implement it?

• I am willing to contribute code towards completing this feature
• I am willing to help test preview builds for this feature