Feature/added csharp textmate grammar

[MattMcLennan]

Added text mate grammar for C#

[MattMcLennan]

According to AppVeyor they have increased the allowed artifact storage. Can we get the AppVeyor to be rurun for this pull request @Akin909

https://help.appveyor.com/discussions/problems/16350-oni-maximum-allowed-artifact-storage-size-of-70000-mb-will-be-exceeded

[CrossR]

Changes look good, thanks for the contribution!

Just need to wait for the CI, then can be merged.

[codecov]

Codecov Report

Merging #2539 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2539   +/-   ##
=======================================
  Coverage   44.76%   44.76%           
=======================================
  Files         351      351           
  Lines       14301    14301           
  Branches     1865     1865           
=======================================
  Hits         6402     6402           
  Misses       7673     7673           
  Partials      226      226

Impacted Files	Coverage Δ
...src/Services/Configuration/DefaultConfiguration.ts	87.5% <ø> (ø)	⬆️

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