Add command to display language server output panel

[DonJayamanne]

For #7459

[codecov-io]

Codecov Report

Merging #7461 into master will increase coverage by 0.31%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##           master    #7461      +/-   ##
==========================================
+ Coverage   58.23%   58.55%   +0.31%     
==========================================
  Files         494      494              
  Lines       21785    21806      +21     
  Branches     3484     3495      +11     
==========================================
+ Hits        12687    12768      +81     
+ Misses       8309     8246      -63     
- Partials      789      792       +3

Impacted Files	Coverage Δ
.../client/activation/languageServer/outputChannel.ts	88.23% <81.81%> (-11.77%)	⬇️
src/client/common/process/logger.ts	86.95% <0%> (-13.05%)	⬇️
src/client/common/liveshare/liveshare.ts	21.42% <0%> (-4.66%)	⬇️
...atascience/interactive-window/interactiveWindow.ts	24.71% <0%> (-0.29%)	⬇️
src/client/common/constants.ts	100% <0%> (ø)	⬆️
src/client/datascience/jupyter/jupyterExecution.ts	57.24% <0%> (+0.09%)	⬆️
src/client/language/characters.ts	33.33% <0%> (+2.56%)	⬆️
src/client/common/utils/version.ts	81.48% <0%> (+3.7%)	⬆️
src/client/providers/providerUtilities.ts	88.88% <0%> (+5.55%)	⬆️
src/client/datascience/cellFactory.ts	89.65% <0%> (+13.79%)	⬆️
... and 6 more

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[karrtikr]

Also also, I don't see tests for the changes. Please do add the tests. Sorry didn't notice this earlier.

[DonJayamanne]

Also also, I don't see tests for the changes. Please do add the tests. Sorry didn't notice this earlier

Oh yes, you're right. Oops