feature: Add a language server?

[Velrok]

The Language Server Protocol allows for real time feedback in code.

The packs gem could provide its dependency violations as LSP diagnostic feedback, which would allow real time feedback on where someone might introduce a dependency by accident.

I see that there is already something similar in the works for vs code.
But having that function as a service, that speaks the LSP would make this available to a wide range of editors, including VS Code, NeoVim, Emacs and more.

[tstannard]

Hi Velrok,
This sounds like a great idea. We are happy to look at a pull request if you put one up!