Meta api for form fields

Continuation from the discussion #709. Listeners are implemented, however the meta field is yet to be started.

The proposal is to have the meta data available to the field component:

(example shamelessly ripped form #709)

<form.Field
  name="foo"
  meta={({ fieldApi }) => ({
    disabled: fieldApi.form.getFieldValue('someOtherField') == null,
    ...
  })}
  // or maybe expose values directly like form.Subscribe
  meta={({ values }) => ({
    disabled: values.someOtherField == null,
    ...
  })}
>
  {(field, meta) => <Comp
    disabled={meta.disabled}
    ...

You can subscribe to the meta from the Form but its pretty handy to have it available to the Field component.

I'm happy to give this a go, I just need the go ahead from a maintainer. 🤟

Start by reading the existing Form.Field API and the form.Subscribe pattern described in the issue. Compare how field components currently receive their arguments, then define how meta should be exposed and how the proposed callback or direct-values API behaves. Done means the Field component can access subscribed meta data as shown in the example, with the behavior agreed by a maintainer.