Wrappers/helpers for async operations

[ianprime0509]

Example of where this would help: https://github.com/ianprime0509/nonograms/blob/5556297d10584502b84535ec258d02931254389d/src/main.zig#L300

Maybe try to detect such async methods and create a new async namespace for each type (similar to signals, etc.) with wrapper functions.

Further reading with some heuristics on detecting async method pairs: https://gitlab.gnome.org/GNOME/gobject-introspection/-/issues/28