Code Lenses not appearing in Unit Tests when using the new language server

[DonJayamanne]

The functionality is disabled as symbol definitions wasn't available until #1934

[DonJayamanne]

Users @ EuroPython (Intellicode + New language server) have already come across this issue.

Depends on #2050 and #2197

[ericsnowcurrently]

Repro:

With the following, code lenses show up with Jedi but do not when using the language server.

# files:
tests/
   __init__.py
   spam.py

# tests/test_spam.py
import unittest

class SpamTests(unittest.TestCase):
    def test_all(self):
        self.assertTrue(False)