♻️ [open-formulieren/open-forms#4929] Take initial data reference fro…

…m query instead of prop

The FormStart component now grabs the initial data reference directly
from the URL parameters rather than requiring the parent component needing
to do this and pass it down as a prop. This is a first step towards not
needing to specify props at all to FormStart so that it can be included
in the data router routes (statically).

src/components/FormStart/index.jsx

@@ -20,6 +20,7 @@ import AuthenticationOutage, {
 } from 'components/auth/AuthenticationOutage';
 import {UnprocessableEntity} from 'errors';
 import {IsFormDesigner} from 'headers';
+import useInitialDataReference from 'hooks/useInitialDataReference';
 import useStartSubmission from 'hooks/useStartSubmission';
 import useTitle from 'hooks/useTitle';
 import Types from 'types';
@@ -42,7 +43,7 @@ const FormStartMessage = ({form}) => {
  * This is shown when the form is initially loaded and provides the explicit user
  * action to start the form, or present the login button (DigiD, eHerkenning...)
  */
-const FormStart = ({form, submission, onFormStart, onDestroySession, initialDataReference}) => {
+const FormStart = ({form, submission, onFormStart, onDestroySession}) => {
   const hasActiveSubmission = !!submission;
   const isAuthenticated = hasActiveSubmission && submission.isAuthenticated;
   const doStart = useStartSubmission();
@@ -70,6 +71,8 @@ const FormStart = ({form, submission, onFormStart, onDestroySession, initialData
     }
   }, [doStart, hasAuthErrors, onFormStart]);
 
+  const {initialDataReference} = useInitialDataReference();
+
   // do not re-render the login options while we're redirecting
   if (doStart && !hasAuthErrors) {
     return (