Take System dlls from testhost folder

[Evangelink]

Description

For TestHostNetFramework folder, embed dlls from the various net framework folders of the testhost projects rather than from netstandard library package.

Related issue

Relates to AB#1843962
Fix #4549

[nohwnd]

Tested on windows and on linux and can run tests in both.

n@RDESKTOP:~$ dotnet exec /mnt/s/p/vstest2/artifacts/packages/Debug/Shipping/Microsoft.TestPlatform.CLI.17.8.0-dev/conte
ntFiles/any/netcoreapp3.1/vstest.console.dll t/mstest2/bin/Debug/net472/mstest2.dll
Microsoft (R) Test Execution Command Line Tool Version 17.8.0-dev (x64)
Copyright (c) Microsoft Corporation.  All rights reserved.

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.

Passed!  - Failed:     0, Passed:     1, Skipped:     0, Total:     1, Duration: 111 ms - mstest2.dll (net472)
n@RDESKTOP:~$

[JamesNK]

Hi

Will this fix make it into .NET 8? I tested with the latest daily SDK for .NET 8 RC1, and it still fails.

Microsoft (R) Test Execution Command Line Tool Version 17.7.0-preview-23317-01+919ec8358820228cc5fa77ef000051c1d6875399 (x64)
Copyright (c) Microsoft Corporation.  All rights reserved.

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
Testhost process for source(s) '/home/runner/work/grpc-dotnet/grpc-dotnet/test/Grpc.Core.Api.Tests/bin/Release/net472/Grpc.Core.Api.Tests.dll' exited with error: Unhandled Exception:
System.TypeInitializationException: The type initializer for 'Microsoft.VisualStudio.TestPlatform.ObjectModel.EqtTrace' threw an exception. ---> System.TypeLoadException: Could not load type of field 'Microsoft.VisualStudio.TestPlatform.ObjectModel.PlatformEqtTrace:TraceSourceLevelsMap' (1) due to: Could not resolve type with token 01000019 from typeref (expected class 'System.Diagnostics.TraceLevel' in assembly 'System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089') assembly:System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 type:System.Diagnostics.TraceLevel member:(null)
   --- End of inner exception stack trace ---
  at Microsoft.VisualStudio.TestPlatform.TestHost.Program.Main (System.String[] args) [0x00033] in <e7703d16410b4b2f944f9c05b9b253d1>:0 
Error:  FATAL UNHANDLED EXCEPTION: System.TypeInitializationException: The type initializer for 'Microsoft.VisualStudio.TestPlatform.ObjectModel.EqtTrace' threw an exception. ---> System.TypeLoadException: Could not load type of field 'Microsoft.VisualStudio.TestPlatform.ObjectModel.PlatformEqtTrace:TraceSourceLevelsMap' (1) due to: Could not resolve type with token 01000019 from typeref (expected class 'System.Diagnostics.TraceLevel' in assembly 'System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089') assembly:System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 type:System.Diagnostics.TraceLevel member:(null)
   --- End of inner exception stack trace ---
  at Microsoft.VisualStudio.TestPlatform.TestHost.Program.Main (System.String[] args) [0x00033] in <e7703d16410b4b2f944f9c05b9b253d1>:0 
. Please check the diagnostic logs for more information.

I see the version is 17.7.0 while the version that you tested is 17.8.0.