Port custom changes from old fork of python language server

[OlegWock]

This PR adds custom code we made to our previous fork of python language server, except changes related to linting, as we don't support it currently. And it adjusts format of hover info to match previous version

Changes made to previous LS for you convenience

[ondrejromancov]

Nice! I see that there are some minor differences between the changes but that's expected.

It's a little difficult to test these changes now so I think that the best thing to do would be to merge and test this version of the work in the web-app.