This PR tweaks the logic for showing the discard changes confirmation modal in the patient registration form. Previously, the modal was being shown in cases where the user had not made any changes. Now, the modal will only be shown when the user has made changes and attempts to navigate away from the form. This is done by checking whether any of the form fields have been [touched](https://formik.org/docs/api/formik#touched--field-string-boolean-). This aligns with the expected behavior of the form and provides a better user experience.

Also, this PR refactors the `DeleteIdentifierConfirmationModal` to leverage Carbon's ModalHeader, ModalBody, and ModalFooter components. It also refactors its registration in the `routes.json` file so it leverages the `modal` property of the route definition. This aligns with our best practices for registering modals.