Pass setter to the `Validate` callback.

[MiroslavPetrik]

Is your feature request related to a problem? Please describe.
I have a special listAtom which has each list item wrapped as an internal formAtom. When validating a form with the listAtom, I need to also validate the internal forms. For that, the set(form.validate, event) must be called.

Describe the solution you'd like
Simply extend the Validate callback to also get the set jotai function.

Describe alternatives you've considered
None