Format using ocamlformat

[rgrinberg]

Does it make sense to vendor ocamlformat and all of its dependencies for this?

[andreypopp]

I'd like to be able for ocaml-lsp to use ocamlformat program installed by opam/esy ‚ I think it's important for users to be able update ocamlformat and ocaml-lsp independently.

If for some group of users (thinking of vscode) we want to provide a workflow which doesn't requires opam/esy then we can ship an ocamlformat binary prebuilt with vscode extension and make sure ocaml-lsp can find it.

[rgrinberg]

Okay, that sounds like a convincing argument against vendoring ocamlforamt itself. It's especially important given that the version of ocamlformat must be mandated for all contributors.

[smorimoto]

Implemented in #89.