Add function to skip a test case

[MichaelHuth]

Add function like IUTF_SKIP() that aborts the test case immediately and treats it as skipped. The function should output INFO(...) text if available. Any setup reentry functions are automatically unregistered.

Use case: If a test case detects that e.g. hardware requirements are not met in a specific setup configuration then it can be setup to be skipped.

[t-b]

Other test frameworks have that as well. See https://docs.pytest.org/en/6.2.x/skipping.html#skipping-test-functions and https://github.com/boostorg/test/issues/139.

[t-b]

I think we should implement this nowish for the sutter tests, Max can do the review.