[WIP] Use symbol provider from new language server to place code lenses in tests

[DonJayamanne]

Fixes #1948

• Title summarizes what is changing
• Includes a news entry file (remember to thank yourself!)
• Unit tests & code coverage are not adversely affected (within reason)
• Works on all actively maintained versions of Python (e.g. Python 2.7 & the latest Python 3 release)
• Works on Windows 10, macOS, and Linux (e.g. considered file system case-sensitivity)
• Dependencies are pinned (e.g. "1.2.3", not "^1.2.3")
• package-lock.json has been regenerated if dependencies have changed

[DonJayamanne]

This relies on #2050

[codecov]

Codecov Report

Merging #2197 into master will decrease coverage by 0.04%.
The diff coverage is 68%.

@@            Coverage Diff            @@
##           master   #2197      +/-   ##
=========================================
- Coverage   79.84%   79.8%   -0.05%     
=========================================
  Files         310     312       +2     
  Lines       14359   14394      +35     
  Branches     2547    2558      +11     
=========================================
+ Hits        11465   11487      +22     
- Misses       2882    2895      +13     
  Partials       12      12

Flag	Coverage Δ
#MacOS	73.94% <68%> (-0.02%)	⬇️
#Windows	74.11% <68%> (ø)	⬆️

Impacted Files	Coverage Δ
src/client/unittests/codeLenses/main.ts	88.88% <ø> (ø)	⬆️
src/client/unittests/types.ts	100% <ø> (ø)	⬆️
src/client/activation/serviceRegistry.ts	100% <100%> (ø)	⬆️
src/client/unittests/main.ts	46.69% <100%> (ø)	⬆️
src/client/activation/jedi.ts	94% <100%> (+0.12%)	⬆️
src/client/providers/symbolProvider.ts	80% <100%> (-6.54%)	⬇️
src/client/activation/symbolProvider.ts	20% <20%> (ø)
src/client/unittests/codeLenses/testFiles.ts	32.78% <26.31%> (-0.27%)	⬇️
src/client/activation/languageServer.ts	26.2% <37.5%> (+0.11%)	⬆️
src/client/providers/throttledSymbolProvider.ts	97.05% <97.05%> (ø)
... and 8 more

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[d3r3kk]

When you get a moment, rebuild this PR, the mac agents recently were updated to python 3.7.

[brettcannon]

@DonJayamanne is this still a WIP?

[brettcannon]

@DonJayamanne #2456 is this PR to just add language server support so we can get it for this release.

[DonJayamanne]

closing as the work has been completed in another PR by @ericsnowcurrently