Add support for tests execution on Mac

[Kolfering]

We have now some replay tests and a setup for UTs in place in /tests but those are only compilable and runnable on Windows.

The way it's done on Windows is instead of having one exe vsproject with all the code like before, there is now 3.
Two exe projects; one for Aleph One, and one for the tests executable and a library linked to the other two with all the Aleph One code.

The tests use the catch2 library from vcpkg and since both Windows & Mac use vcpkg, it's already installed on Mac.
The tests executation is integrated in CI and are ran on every push, after the build.
How to run them can be found at /.github/actions/run-tests