The CAA Release Group cover art provider is a useful fallback in case there is no cover art for a release. It might also satisfy users which otherwise would want to add a wrong cover art to the release just to get some result.

This is a weaker version of what is requested at PICARD-2109

See also:

• https://github.com/metabrainz/picard/pull/1743
• PICARD-2109