feat: Query alternative Git forges

[toastal]

Is your feature request related to a problem? Please describe.
All of the listed color scheme originate from GitHub. This is not the only Git forge and Git is meant to work in a distributed / decentralized setting. If it wasn't for needing to communicate with many other projects and my contract work, I would not be a part of this closed-source, Microsoft-owned, social-network-oriented Git forge. I am currently in a beta phase for my own theme hosted on Sourcehut, and I was looking at what I may need to include to get it listed on one of these aggregated lists to find out that without mirroring I could never make vimcolorschemes (one of the top web search results). Given that I don't want any of my personal code to be subject to Microsoft GitHub's terms of service (including use in Copilot), mirroring will never happen.

While I selfishly would prefer as many projects as possible to abandon GitHub, especially GPL projects, this isn't practical. However, favoring one particular Git forge is problematic and leads to more people feeling coerced to use a centralized server because of existing integrations.

Describe the solution you'd like
Your query should include at a bare minimum the same search on GitLab, Sourcehut (searching via tags could be reasonable as well), and Codeberg (Gitea-powered), with the ability for users to upload additional, self-hosted options (including self-hosting the aforementioned forges (because unlike GitHub they are all open-source), but also cgit, etc.). Data will likely need to be marshaled as the queries results won't match across various APIs and some fields, like the social networking and gamification metrics (e.g. "stargazers"), will be missing, but they should not prevent a project from being listed.

Is the current list of projects on these platforms low? Currently, yes, but Vim bundlers have historically given GitHub unfair, special treatment with shorthands like $username/$repo. I believe if tooling and discoverability is improved, then we may see users realizing and feeling empowered to use their many options.

[reobin]

Hey @toastal !

Thank you for this write up.

I agree 100% with everything said in there. vimcolorschemes started as a small personal project, and the Github API made the most sense at the time.

I created vimcolorschemes/worker#34 to follow the progress and investigation of the alternative git forges.