Function cache_generated_file

Lower-level caching function. Given some arbitrary file name (and optional path components) relative to the cache path, if the file exists, returns the fully qualified path to the file in the cache, if not, it passes that fully qualified path to the provided closure, and if that closure succeeds and the file was created, then this function returns the fully qualified path. If the closure returns

(
    cache_path: &Path,
    results_path: &Path,
    f: F,
)