Explore ways of packaging the dependencies correctly

[giltho]

Right now, we're vendoring every dependency. However, some dependencies may be annoying, like uri, because they themselves have widely-used dependencies (in this case re), and we don't want to force a re user to have a version compatible with uri to be able to use the language server.

I have no idea of the current state of the project or even if it could be used, but maybe duniverse could be a solution here. Every of ocaml-lsp's dependency is built by dune. That way we could even reduce the amount of libraries we vendor through submodules. @avsm What do you think ? :)

Of course that is one possibility, but we can explore others

[rgrinberg]

@tmattio is working on automating installation. Once that is done, this should no longer be a problem.