Prevent "are you sure you want to leave?" popup

If the user clicks on the "Ask to join" button, they are trying to
abandon the form so we don't want to ask them if they want to preserve
the data previously entered.

frontend/src/routes/(authenticated)/project/create/+page.svelte

@@ -51,7 +51,7 @@
 
   //random guid
   let projectId:string = crypto.randomUUID();
-  let { form, errors, message, enhance, submitting } = lexSuperForm(formSchema, async () => {
+  let { form, errors, message, enhance, submitting, tainted } = lexSuperForm(formSchema, async () => {
     const result = await _createProject({
       id: projectId,
       name: $form.name,
@@ -174,6 +174,7 @@
   async function askToJoinProject(projectId: string, projectName: string): Promise<void> {
     await _askToJoinProject(projectId);
     notifySuccess($t('project.create.join_request_sent', { projectName }))
+    $tainted = undefined; // Prevent "are you sure you want to leave?" warning
     await goto('/');
   }
 </script>