Function ensure_directory 

pub fn ensure_directory(
    path: &Path,
    strategy: DirectoryCreationStrategy,
) -> Result<(), PathError>

Ensure the provided directory exists and is writable according to the chosen strategy.

If the directory exists, verifies it’s actually a directory and is writable. If the directory doesn’t exist, behavior depends on strategy:

• AutoCreate: Creates the directory (and parents)
• Disallow: Returns an error