Add setting to control speed of diagnostic publishing

[MikhailArkhipov]

Fixes #2270

• 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)

microsoft/PTVS#4612

[d3r3kk]

Looks just fine 👍, but let's add a few tests before we submit...

[codecov]

Codecov Report

Merging #2357 into master will increase coverage by 0.14%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2357      +/-   ##
==========================================
+ Coverage   75.98%   76.13%   +0.14%     
==========================================
  Files         309      309              
  Lines       14341    14341              
  Branches     2540     2540              
==========================================
+ Hits        10897    10918      +21     
+ Misses       3434     3413      -21     
  Partials       10       10

Flag	Coverage Δ
#MacOS	74.17% <100%> (ø)	⬆️
#Windows	74.33% <100%> (+0.06%)	⬆️

Impacted Files	Coverage Δ
src/client/activation/languageServer.ts	26.08% <100%> (ø)	⬆️
src/client/linters/lintingEngine.ts	91.15% <0%> (-0.89%)	⬇️
src/client/linters/baseLinter.ts	95.78% <0%> (+6.31%)	⬆️
src/client/common/application/applicationShell.ts	30.76% <0%> (+7.69%)	⬆️
src/client/common/logger.ts	68.42% <0%> (+10.52%)	⬆️
src/client/linters/errorHandlers/errorHandler.ts	100% <0%> (+22.22%)	⬆️
src/client/linters/errorHandlers/notInstalled.ts	100% <0%> (+55.55%)	⬆️

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[MikhailArkhipov]

Tests for the delay? We'll add those to LS repo when Alex is done porting tests.

[MikhailArkhipov]

microsoft/PTVS#4612

[d3r3kk]

Tests for the delay? We'll add those to LS repo when Alex is done porting tests.

I'm not worried about the delay, this is only a config change. Please pardon my unfamiliarity with how the LS gets it's config settings, I had assumed that VSCode-Python sets them into the LS at some point in the code.

My request for tests would simply to be 'Check that the value set in the config is being sent to the LS', but perhaps that is read directly from our package by the LS itself?

[MikhailArkhipov]

Yep, LS reads it directly. https://github.com/Microsoft/PTVS/blob/master/Python/Product/VSCode/AnalysisVsc/LanguageServer.cs#L155

[d3r3kk]

Good to know, thanks!