* remove some try catches choking all exceptions
* rename ExceptionExtension to ReportAsWarning, show full stack instead of just message
* dotnet-migrate try catch clean-up
* fix migration test failures
This enables users to use the CLI on newer versions of the OS that aren't fully supported yet - for example using a new OSX version that isn't listed in the runtime graph in the current NuGet packages.
Fix#4238
The BuiltInCommandTests sets the current Console.Out and Console.Error, which causes the test to fail if some other test is running and writes to the console at the same time.
Fix#2768