Context:

The CMake helper 'create_test_executable' supports an option to sync a directory over to the build directory: 'ADDITIONAL_DIRECTORIES'.

When creating a test executable we may want to sync the contents of a directory (such as a set of configs). This being a path we want the test executable to be able to access when running in its binary location. This in particular is used by the CPP suite. 

Problem:

CMake currently won't detect and sync over new files added to the source directory. It only copies over the contents of a directory that are seen at the initial configuration time. We want CMake to sync over new files as they are added, whenever a subsequent configuration step is run. We possibly want to use the CMake feature: CONFIGURE_DEPENDS (https://cmake.org/cmake/help/latest/command/file.html#glob).