Draft: [room.ide, common lsp] Intial prototype for delegated target code completion

TODOs:

• Cleanup
• Should only provide completion documents for the currently selected target language
• Try to get completions from CDT if in eclipse(?)
• Try to get diagnostics from CDT if in eclipse(?)
• Generate wrapper for Dataclass + Portclass
• Generate stubs for used dataclasses or add the correct imports
• Generate stubs for used enums or add the correct imports