Added VS Code syntax highlighting for Beluga

[thesophiaxu]

For people who want an editor from later than last century.

I've created the extension package (.vsix) file and I can give you guys the source code/package if anyone is interested.

[Ailrun]

Thanks for the issue! Any contribution is welcomed.

One concern is that, none of the maintainers use VScode so I'm not sure we have resource to maintain the extension.

[zlin888]

Hi @thesophiaxu, I am quite interested in it! Could you share it with me? :)

[MartyO256]

TextMate language grammars only support context-free languages, but Beluga and Harpoon are context-sensitive. That is, we could only reliably highlight the syntax for keywords and comments with a TextMate language grammar as shown in the screenshot.
If we want to fully implement syntax highlighting for Beluga and Harpoon in Visual Studio Code, we'll need to implement an extension with semantic highlighting as in this sample, and using the external syntax modules. The only LSP server implementation I know about written in OCaml is ocaml-lsp.