Consider using flags to specify whether path or name is returned

[fhightower]

For example, rather than having directory_subdirectory_names and directory_subdirectory_paths, simply have directory_subdirectories(dir_path: str, return_paths: bool = False) where the return_paths flag determines whether the returned items are paths or file names.

This would involve consolidating and simplifying the code and interfaces in this library.

This ticket also involves changing the function calls in all of the democritus libraries that use these functions.

[fhightower]

This also applies to the directory_file_names_matching and directory_file_paths_matching functions.