Update debugger to 1.23.8

[gregg-miskelly]

• Updated the version of .NET that the debugger uses for running its own C# code to .NET 5
• Updated .NET debugging services loader to address problem with debugging after installing XCode12 (dotnet/runtime/#42311)
• Fixed integrated terminal on non-Windows (#4203)

[codecov]

Codecov Report

Merging #4281 (1ce87c2) into master (0e14b45) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4281   +/-   ##
=======================================
  Coverage   85.99%   85.99%           
=======================================
  Files          60       60           
  Lines        1857     1857           
  Branches      215      215           
=======================================
  Hits         1597     1597           
  Misses        200      200           
  Partials       60       60           

Flag	Coverage Δ
integration	100.00% <ø> (ø)
unit	85.99% <ø> (ø)

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