read_file_to_codes/3 and others in readutil require options to be a list

[rla]

read_file_to_codes/3 and others in readutil require options to be a list while many other options-taking predicates also accept dicts.

Link to code: https://github.com/SWI-Prolog/swipl-devel/blob/470019184cfb99e228a4194183b69709784dd3ab/library/readutil.pl#L215

[JanWielemaker]

This is the case for most library foreign predicates processing options. Probably we need to expose the core system option processing to the foreign API.