CTest can't forward command line arguments to the test runner, so add
the option to using an environment variable to enable features instead.
CMake issue tracking the feature that would have been needed:
https://gitlab.kitware.com/cmake/cmake/-/issues/20470
Tests which aren't passing yet have been disabled in CI.
Instead of using an environment variable, pass the path to the config
file as a command line argument. This makes it possible to directly
copy the command being run (as show with --verbose) and run it in a
debugger outside of the test framework.
Old verbose output:
Running: /home/ajor/src/object-introspection3/build/test/integration/integration_test_target oil cycles_unique_ptr
New verbose output:
Running: /home/ajor/src/object-introspection3/build/test/integration/integration_test_target oil cycles_unique_ptr /home/ajor/src/object-introspection3/build/testing.oid.toml
