Setup VS Code Client and Initialize LSP

[Francisco-Galindo]

We need to establish the JSON-RPC connection between VS Code and the Server for so we can test the changes we do.

Checklist:

• Scaffold VS Code extension (check this.
• Configure LanguageClient to launch the server executable (made from harels.go).
• Implement server-side initialize request.
• Define capabilities (we only need textDocumentSync for now) in the server response.
• Redirect server stderr to the VS Code Output.