* [tests] Add a .NET/macOS version of monotouch-test.
I made a macOS version of monotouch-test instead of a .NET version of xammac tests,
so that one day we might have only one test suite for all our API tests.
* Add a project file for .NET/macOS
* Fix some code to handle the fact that we're called 'monotouchtest' on macOS (but
only on .NET).
* Ignore exception marshalling tests, those aren't working yet.
* [xharness] Add support for .NET/macOS and add a macOS version of monotouch-test to our tests
* [dotnet-linker] Skip libSystem.Net.Security.Native and libSystem.Native when collecting native methods to preserve for .NET/macOS.
Refactor TestProject so that we can move all the tasks to the common
assembly. We had to remove all the references from Harness, that
included the MonoNativeInfo.
Rolf Bjarne Kvinge
Přemek Vysoký
Manuel de la Pena