Support discovery/indexing datasets from forgejo-aneksajo instances

[yarikoptic]

https://codeberg.org/matrss/forgejo-aneksajo

known instances:

• https://hub.datalad.org
• ...

at worst could be all repositories similar to GIN I guess.

Related (also to interegrate/use API, has pointers):

• forgejo support con/tinuous#194

[matrss]

Another instance: https://atris.fz-juelich.de/

Since Forgejo is a descendant of Gitea, which is a descendant of Gogs, I wouldn't be surprised if the existing code for GIN can be easily adapted to index forgejo-aneksajo instances as well.

[yarikoptic]

indeed. Likely could be started as what we have for GIN already -- getting all of them but may be adding some extra sensing/filtering later on to blacklist/not consider some.