Introduce %%pyproject_check_import
    
    %%pyproject_save_files newly saves also a list of importable modules.
    The list is used by %%pyproject_check_import to invoke the import test
    on each module name.
    %%pyproject_check_import accepts two options:
    -t: filter only top-level modules
    -e: exclude module names matching the given glob from the import check