added logic to save collections and display them

lib/widgets/create_bookmark_collection_dialog.dart

@@ -2,13 +2,19 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 class CreateBookmarkCollectionDialog extends StatelessWidget {
-  const CreateBookmarkCollectionDialog({super.key});
+  const CreateBookmarkCollectionDialog({
+    super.key,
+    required this.onSavePressed,
+  });
+  final void Function(String name) onSavePressed;
 
   @override
   Widget build(BuildContext context) {
+    final nameController = TextEditingController();
     return AlertDialog(
       title: Text('Create Collection'),
       content: TextField(
+        controller: nameController,
         autofocus: true,
         maxLines: 1,
         maxLength: 50,
@@ -22,7 +28,13 @@ class CreateBookmarkCollectionDialog extends StatelessWidget {
         ),
       ),
       actions: [
-        FloatingActionButton(onPressed: () {}, child: Icon(Icons.save)),
+        FloatingActionButton(
+          onPressed: () {
+            onSavePressed(nameController.text);
+            Navigator.of(context).pop();
+          },
+          child: Icon(Icons.save),
+        ),
       ],
     );
   }