Upgrade `dmypy` to a language server (LSP)

Feature

I would like for dmypy to be a fully fledged language server. Obviously it would only support diagnostics (which would make this much simpler). But this would be very convenient from an editor point on view given the direction editor tooling is going.

Could probably use something like https://github.com/openlawlibrary/pygls to handle the low level details of LSP.

Pitch

Most editors and their plugins shell out and call mypy. But this can be quite slow on some projects since it needs to cold start every time (except for .mypy_cache).

Inizia leggendo l’implementazione di dmypy e la specifica LSP, quindi valuta pygls come libreria di basso livello proposta. Definisci come dmypy debba esporre le diagnosi tramite LSP e individua i test dell’editor o del protocollo necessari per verificare il server. Il lavoro è completato quando dmypy funziona come language server che fornisce diagnosi agli editor.