Error message when dotnet runtime not found is unclear

[Evangelink]

Describe the bug

Muxer is not found on the machine.

Steps To Reproduce

Try to run dotnet test --arch arm64 on a machine where arm64 is not available. You will get the following error message:

 C:\Users\<redacted>\.nuget\packages\microsoft.testing.platform.msbuild\1.4.3\buildMultiTargeting\Microsoft.Testing.Platform.MSBuild.targets(320,5): error : Full path tool calculation failed. Runner 'dotnet.exe'

Expected behavior

An error similar to VSTest:

Could not find 'dotnet.exe' host for the 'ARM64' architecture.

You can resolve the problem by installing the 'ARM64' .NET.

The specified framework can be found at:
  - https://aka.ms/dotnet-download