Function direct_key_certification_dirs_from_dir 

fn direct_key_certification_dirs_from_dir(
    path: impl AsRef<Path>,
) -> Result<Vec<DirectKeyCertificationDir>, Error>

Creates a list of direct key certification directories from a directory.

Errors

Returns an error if

• path does not have a subdirectory named CERTIFICATION_DIR, or reading entries from that subdirectory fails,
• the CERTIFICATION_DIR subdirectory contains paths that are not directories,
• or creating a DirectKeyCertificationDir from one of the paths in the CERTIFICATION_DIR subdirectory fails.