Progress support

[bagel897]

https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#progress
LSP added a progress system. Example Lua Language server:

Could we implement a way to handle this for longer-running items and the overall starting of pylsp?

[ccordoba12]

Hey @bageljrkhanofemus, we don't have time for this right now. But you're welcome to send a pull request to implement that functionality.

[syphar]

This can be closed, since #236 is merged

[ccordoba12]

Right, thanks for pointing that out.