Added placeholder for lastName and role addition functionality

Try to rebase

frontend/pweb/lib/pages/invitations/widgets/form/fields.dart

@@ -8,8 +8,11 @@ import 'package:pweb/generated/i18n/app_localizations.dart';
 class InvitationFormFields extends StatelessWidget {
   final List<RoleDescription> roles;
   final TextEditingController emailController;
-  final TextEditingController nameController;
+  final TextEditingController firstNameController;
+  final TextEditingController lastNameController;
   final TextEditingController messageController;
+  final bool canCreateRoles;
+  final VoidCallback onCreateRole;
   final String? selectedRoleRef;
   final ValueChanged<String?> onRoleChanged;
 
@@ -17,8 +20,11 @@ class InvitationFormFields extends StatelessWidget {
     super.key,
     required this.roles,
     required this.emailController,
-    required this.nameController,
+    required this.firstNameController,
+    required this.lastNameController,
     required this.messageController,
+    required this.canCreateRoles,
+    required this.onCreateRole,
     required this.selectedRoleRef,
     required this.onRoleChanged,
   });
@@ -47,11 +53,21 @@ class InvitationFormFields extends StatelessWidget {
               ),
             ),
             SizedBox(
-              width: 280,
+              width: 200,
               child: TextFormField(
-                controller: nameController,
+                controller: firstNameController,
                 decoration: InputDecoration(
-                  labelText: loc.invitationNameLabel,
+                  labelText: loc.firstName,
+                  prefixIcon: const Icon(Icons.person_outline),
+                ),
+              ),
+            ),
+            SizedBox(
+              width: 200,
+              child: TextFormField(
+                controller: lastNameController,
+                decoration: InputDecoration(
+                  labelText: loc.lastName,
                   prefixIcon: const Icon(Icons.person_outline),
                 ),
               ),
@@ -59,7 +75,7 @@ class InvitationFormFields extends StatelessWidget {
             SizedBox(
               width: 260,
               child: DropdownButtonFormField<String>(
-                initialValue: selectedRoleRef ?? (roles.isNotEmpty ? roles.first.storable.id : null),
+                value: selectedRoleRef,
                 items: roles.map((role) => DropdownMenuItem(
                   value: role.storable.id,
                   child: Text(role.describable.name),
@@ -68,6 +84,11 @@ class InvitationFormFields extends StatelessWidget {
                 decoration: InputDecoration(
                   labelText: loc.invitationRoleLabel,
                   prefixIcon: const Icon(Icons.security_outlined),
+                  suffixIcon: IconButton(
+                    onPressed: canCreateRoles ? onCreateRole : null,
+                    icon: const Icon(Icons.add_circle_outline),
+                    tooltip: loc.invitationAddRoleButton,
+                  ),
                 ),
               ),
             ),