Member resolver: let a resolver also map keyword names #34

Follow-up to #17. A member resolver maps a member name (fill_max_width -> fillMaxWidth), but keywords on proxy methods stay Kotlin names (m.padding(paddingValues=...)), while pythonx-compose already maps keywords for module-level functions.

Decided: a resolver may return (kotlin_name, keyword_map) instead of kotlin_name, where keyword_map is {python_kw: kotlinParam} applied when calling that member. Returning a plain name keeps today's behaviour. The binder still renames nothing on its own.

Completion: m.padding(padding_values=...) works with a resolver that returns a keyword map; an unknown keyword still raises TypeError naming the Kotlin parameters; with no resolver, behaviour unchanged; tamper check.