[Feature] `rocks --lsp` command for `rocks.toml`

[mrcjkb]

• We already have all the logic needed to query luarocks,org (except for custom servers like rocks-binaries) and parse versions, etc.
• This could be used by rocks.nvim to provide
  • Diagnostics about outdated or out-of-sync[^1] rocks
  • Code actions for editing rocks.toml
  • Completions for rocks and versions

[^1]: Would need the ability to query installed rocks - which has a different tree structure than rocks when installed with luarocks.

• Not entirely sure if rocks is the right tool for this, but I think it would have better performance being in a separate process than within Neovim.
• Would we want a separate rocks-lsp-lib crate, to keep it separate from rocks-lib?

[vhyrro]

If the LSP is "lightweight enough" (which I can imagine it being, since it's just reading a TOML file and providing basic diagnostics by using the library), we could happily make a rocks lsp subcommand that would launch the LSP.

We could gate this behind a feature flag for convenience, if someone really doesn't want the subcommand nor its dependencies :)