Add `new Intl.DateTimeFormat().resolvedOptions().hour12`

[Ayc0]

According to the spec, new Intl.DateTimeFormat().resolvedOptions() should return an object with hour12 in it.
But this is unset in all browsers.

Should we add a section about this in caniuse?

Cf https://twitter.com/BenJ_Ayc0/status/1669609549622394880?s=20