Create LSP server and client

[SpaceManiac]

Using the parser from #1, create a server for the Language Server Protocol.

Low priority.

Possible features:

• Parser diagnostics
• Code completion for keywords and entity names
• Go to definition
• Find all references

Add a client that can talk to this language server to the VSC plugin in starstream_vscode/.

Protocol specification: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/
VSC client guide: https://code.visualstudio.com/api/language-extensions/language-server-extension-guide
Useful libraries:

• https://docs.rs/lsp-types/latest/lsp_types/
• https://docs.rs/jsonrpc-core/latest/jsonrpc_core/