Add coq-lsp to Coq Platform about platform

[ejgallego]

Thanks @Zimmi48 for both the suggestion to do this and the help with setting the right meta-data.

We have discussed a bit on the coq-lsp side and we think 0.1.4 (or 0.2.0) should offer the right compatibility story for the 8.17 release, so that's the version we will target for inclusion.

The main compatibility story is that client and server need to agree on the (only important) extension our LSP has, the goals request.

We have now a plan that should handle different versions reasonably.

[ejgallego]

The depending PRs are ready / merged, thus I'm requesting inclusion, IIUC the guide states 4 TODO points:

• Packages are typically included on user request via a github issue.

This issue should work.

• Requests should contain a justification.

coq-lsp is of help to IDE users (VS Code client exists, server is usable within the standard) , moreover, coq-lsp is posed to replace SerAPI and sertop, so making testing easy is IMHO important.

• The author(s) or current maintainer(s) of the package shall agree to the inclusion of their package in the Coq Platform. This means that they agree to put reasonable effort into releasing a version of the package compatible with each new Coq release shortly after every Coq release and to maintain some relative stability between each release. The agreement of the authors is given via a comment in the respective github issue.

I agree and commit to all of this.

• All the dependencies of a platform package are also officially part of the platform.

That's the case now (serlib being the only annoying dep, and is already there).

[ejgallego]

Additionally, if you tell me which file to touch (sorry I couldn't manage to figure this out today) I'll be happy to do the pull request myself.