Rename Validators to Avoid DOM Event Confusion

[crutchcorn]

In my time showcasing TanStack Form, I noticed a lot of confusion around <Field>'s onChange validator comparing to onChange from the <input> HTML event.

Let's solve this by renaming:

<form.Field onChange={z.string()}/>

To:

<form.Field validators={{onChange: z.string()}}/>

This ticket should also include:

• [ ] Renaming the validators to validators prefix property
• [ ] Changing mount validator API to match the others (prev: #429)
• [ ] Adding onSubmit and onSubmitAsync to FormAPI

[aadito123]

Also prefer the 2nd.

[natedunn]

Also in favor of option 2.