Parsing --list-tests is broken, as Catch automatically line wraps the
line when it gets too long, stripping any whitespace in the process.
This means that it's impossible to reproduce the exact name of the
test if the test's name is long enough to line-wrap.

Furthermore, overwriting the LABELS property with the discovered labels
breaks users who manually added custom ctest labels.

Rolling back to using --list-test-names-only for now, as it does not
wrap lines even on very long test names.

We may be able parse the output of --list-tags to produce the ctest labels.
However, the straightforward way of doing this is to use CMake's
get_property(TEST ...) and set_property(TEST ... APPEND ...), which don't
work if the test name has spaces or other special characters. We would
need to mangle the test name to a valid CMake identifier to do it that way.

- `ctest --print-labels` now will show list of available labels
- `ctest -L <regex>` will allow to run tests with given labels(tags)

When using an optional launcher the target name is not interpreted as a
target, therefore it is not replaced automatically with its path.

After the script, the ParseAndAddCatchTests_TESTS property for the
target, and for each source file in the target is set, and contains the
list of the tests extracted from that target, or from that file.

This is useful, for example to add further labels or properties to the
tests.