Optional callbacks for handleSubmit

[danielrkling]

I don't know if this is a common use case, but I sometimes have multiple buttons with a form that each have a different submit action. A simple change that I think accomplishes this is optional parameters for handleSubmit

handleSubmit = async ( 
  onSubmit?: (props: {
      value: TFormData
      formApi: FormApi<TFormData, TFormValidator>
    }) => any | Promise<any>
  onSubmitInvalid?: (props: {
      value: TFormData
      formApi: FormApi<TFormData, TFormValidator>
    }) => void) {
onSubmit ??= this.options.onSubmit
onSubmitInvalid ??= this.options.onSubmitInvalid
// replace options handlers with local handlers

Then I could call handleSubmit with different callbacks on the different buttons.