[Windows] Add `wslMode` to settings

It seems the WSL mode in Windows is very powerful, as it allows to keep all tools in their original OSX/Linux versions and plug them in into the native Windows IDEs.

Adding a setting to enable wslMode would allow Windows users to quickly configure the extension without the need to install bridges or any other hack, and it would allow us to tweak the data that goes from the server to the VSCode client, to make sure everything works properly.

A couple of use cases for this setting:

• Prepending bash -ic to paths: so instead of having to install ocaml-on-windows, just adding this setting on VSCode would work
• Adapting file paths: because bsb or merlin would be running on Linux mode, we would need to adapt from file:///mnt/c/project/myFile.re to C:\project\myFile.re so the diagnostics work properly (underline text on file, double click to open, etc)

There are probably more cases.

@freebroccolo @chenglou @superherointj

[ghost]

@jchavarri yeah, in OCaml.

I’ll just add btw that if someone wants to create a PR for the current implementation that gets WSL working in a robust way, I’m happy to merge that as a temporary measure. I’m just spread a bit thin with other projects at the moment and it’s kind of hard to justify putting a lot more energy into a rewrite of the current server core in typescript if the intention is to move on to something better soon after anyway.

[superherointj]

There was a breakthrough in thinking by realizing BuckleScript couldn’t be used on native Windows because it was generating invalid Merlin files and that was causing problems with Merlin.

• Automating adding ‘bash -ci’ prefix is a convenience change.

• Right now, the most important thing to happen to get extension working w/ Windows & WSL is to fix Unix/Windows path translation issue .

#TheOneWindowsThing