PR: Add LSP support for handling jedi script extra paths and environment

[goanpeca]

Description of Changes

• Wrote at least one-line docstrings (for any new functions)
• Added unit test(s) covering the changes (if testable)

• Tests on actual working of LSP are on Add Jedi support for extra paths and different environment handling palantir/python-language-server#680
• This is part of issue Finish LSP integration #7724.

Issue(s) Resolved

Fixes #10299
Fixes #10646
Fixes #1004

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct: @goanpeca

[pep8speaks]

Hello @goanpeca! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2019-11-17 22:43:56 UTC

[ccordoba12]

@goanpeca, before reviewing this PR, I'd like for you to implement the changes we talked about on your PyLS PR, so we can test both PRs at the same time.

[goanpeca]

before reviewing this PR, I'd like for you to implement the changes we talked about on your PyLS PR, so we can test both PRs at the same time.

Yes, working on this now

[goanpeca]

@ccordoba12 test passed :-) this one is ready!

[ccordoba12]

Thanks a lot @goanpeca!! This is a fantastic addition!