Consider making `vscode-sys` an independent project

[nkitsaini]

I'm building a vscode-extension using wasm and I found this project's vscode-sys is way more extensive compared to https://crates.io/crates/vscode-sys (which is archived now).

Currently I'm using a copy and have added two or three new Api functions for my use case. But I think making vscode-sys a separate project will make it easier for me (or anybody using the project) to push new Api additions, eventually making it more and more extensive.

It'll also be easy to discover.