Filters the URL to redirect the user to after a form submission request has been processed.
If a submission is applicable, its query variable will be appended.
(string) (Optional) URL to redirect to. Default is the original form URL.
(awsmug\Torro_Forms\DB_Objects\Forms\Form) (Optional) Form object.
(awsmug\Torro_Forms\DB_Objects\Submissions\Submission) (Optional) Submission object, or null if no submission.