[cmake] Mark quick tests and python tests

Mark all quick tests using LABELS quick following the pattern in the core modules. This allows to use make build_quick_tests; ctest -L quick to only run those.

Currently these are all tests except the python-related ones. Surprisingly it was the other way around although each python test may take several minutes.

Conversely, if you only want to run the python tests, the others should not harm, because they are run much faster. However, if you don't want to build the others, it's good if you can select the python tests specifically. Hence this also adds the label python to the python tests to allow ctest -L python.