Unit Tests to ensure capabilites in PTVSD match those in debug adapter

[DonJayamanne]

Fixes #1143
Also updated debugger (npm) packages.

This pull request:

• Has a title summarizes what is changing
• Includes a news entry file (remember to thank yourself!)
• Has unit tests & code coverage is 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)

[codecov]

Codecov Report

Merging #1225 into master will increase coverage by 0.11%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1225      +/-   ##
==========================================
+ Coverage   70.94%   71.06%   +0.11%     
==========================================
  Files         266      266              
  Lines       12284    12288       +4     
  Branches     2172     2172              
==========================================
+ Hits         8715     8732      +17     
+ Misses       3445     3436       -9     
+ Partials      124      120       -4

Impacted Files	Coverage Δ
src/client/debugger/mainV2.ts	79.2% <100%> (+7.58%)	⬆️
src/client/linters/lintingEngine.ts	90.35% <0%> (-0.88%)	⬇️
...rc/client/debugger/PythonProcessCallbackHandler.ts	52.3% <0%> (-0.66%)	⬇️

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