Implement a Language Server

[mcchrish]

Is your feature related to a specific framework or general for this extension

No.

Is your feature request related to a problem? Please describe.

Only supports VSCode. While opening all these amazing work done already as a language server means the support can expand to any editor that supports LSP.

Describe the solution you'd like

1. Split the repo into a monorepo with language server and VS code extension as separate packages
2. Publish the language server as an npm package.

Language server has the following functionalities (just the things on top of my head):

• Auto completion items based on the existing translations
• Code actions to create translations from inline text
• Publish missing translation as diagnostics

Additional context

There are templates that can be based on to already do the heavy lifting of starting a language server. Example:
https://github.com/volarjs/volar.js