feat: submitCount OR Add onBeforeSubmit/onAfterValidation hooks

Hello, I am looking for a way to run custom actions after the user pressed Submit button and the form has been validated as invalid.

I need to scroll to first element with custom scrolling library and then to focus that element.

I have seen https://github.com/final-form/react-final-form/issues/39 and [final-form-focus](https://github.com/final-form/final-form-focus), but there is not enough space for customizations.

Solution with `onChange` also doesn't work as scrolling away and pressing Submit again won't trigger this handler (as nothing has changed).

/edit: What would be helpful is a supplement property for all `submit` that would change every time user invokes the submit action. I can think of `submitCount`.

That way, `submitFailed` would stay set and unchanged to `true`, but the submit count would correctly reflect that something has happened even though state (values) has not changed.