Revise parse_registry_path or add a new function to check if path is a valid registry path

[donaldcampbelljr]

          After discussion:

• We should check first if a file was provided, then check if its a proper registry path, then send to PEPHUB.
• Write a function in ubiquerg (or update the existing one) such that the user can pass flags, e.g. require_namespace=True and have it return the parsed path (or a False if it could not parse)

Originally posted by @donaldcampbelljr in pepkit/looper#456 (comment)

[donaldcampbelljr]

From Looper:

def is_pephub_registry_path(input_string: str) -> bool:
    """
    Check if input is a registry path to pephub
    :param str input_string: path to the PEP (or registry path)
    :return bool: True if input is a registry path
    """
    try:
        registry_path = RegistryPath(**parse_registry_path(input_string))
    except (ValidationError, TypeError):
        return False
    return True

The above function (from Looper), should be moved here to Ubiquerg and actually fail if the input is anything other than a valid PEPHub registry path.

[nsheff]

For use in ubiquerg, the function shouldn't be specific to PEPhub, though.