Support lsp-jedi

[QiangF]

It has some benefit compared to pyls. Unlike python-language-server, jedi-language-server:

Uses pygls instead of creating its own low-level Language Server Protocol bindings
Supports one powerful 3rd party library: Jedi. By only supporting Jedi, we can focus on supporting all Jedi features without exposing ourselves to too many broken 3rd party dependencies (I'm looking at you, rope).
Is supremely simple because of its scope constraints. Leave complexity to the Jedi master.

https://github.com/fredcamps/lsp-jedi