Planning for when string traits are available

[idanarye]

I really want to restructure this project using traits: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=61c502a4b4d87058e486bb44870637ad

[idanarye]

One problem with this is that it will allow setting fields with the traits, even if we don't want to show their setters.

Maybe set_field and extract_field should work on the payload instead?