Convert options objects to records with optional fields

[TheSpyder]

There's a new feature in ReScript v10 (which hit alpha today) that means we no longer need annoying functions to implement "option object" apis. I'll update this description with examples when I have time.

We don't use this style in webapi as much as some other bindings, but we should still switch to this during the version 2 efforts.

[Minnozz]

@TheSpyder Do you want to provide the first example(s) or are contributions already welcome?

How do you intend to handle the required bump in compiler version?