Merged requested to merge enable_tests into main
Broken tests are moved back from ftest/disabled/ to ftest/. Prefix "broken." is prepended to their names.
In ftest/CMakeLists.txt, each test with prefix "broken" in its name is assigned the label BROKEN. This allows us to skip these tests using
ctest -LE BROKEN (LE = label-exclude). In particular, this is done in CI.