* Fix system version checks to work properly on Mac Catalyst (which uses the macOS
version as its system version).
* Add the framework-specific defines to the build for monotouch-test.csproj (using
the generated response files), this way we can use them in the tests.
* Sprinkle conditionals in numerous places - I tried using either framework-specific
or XAMCORE_3_0 whenever that made since (instead of using Mac Catalyst as a condition).
* Updated a few tests to use non-deprecated API (because the deprecated API often
doesn't exist in Mac Catalyst).
* Also a few minor API fixes to make any corresponding tests compile.
* [tests] Build the native test library for macOS and create a binding project for it.
Also add the new binding project to the xammac and link all XM test projects,
which allows us to stop excluding tests that require the native library and
the corresponding bindings.
* [tests] Include more tests in xammac_tests.
* [tests] Correctly ignore the ObjC exception tests in release mode.
Rolf Bjarne Kvinge
Timothy Risi
Sebastien Pouliot