vscode-language-mugene

This part was mostly copied from https://github.com/matarillo/vscode-languageserver-csharp-example except that we have our own mugene language server. Though there have been some changes and I don't remember what it used to be like anymore.

To build the extension, run npm install and npm run compile. It will automatically run msbuild to build C# baaed LSP service. F5 from vscode does not fully build the C# part.