Add game_template (#1180)

Adds a template / sample for games built in Flutter, with all the bells and whistles, like ads, in-app purchases, audio, main menu, settings, and so on.

Co-authored-by: Parker Lougheed
Co-authored-by: Shams Zakhour

game_template/lib/src/settings/custom_name_dialog.dart

@@ -0,0 +1,75 @@
+// Copyright 2022, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:game_template/src/settings/settings.dart';
+import 'package:provider/provider.dart';
+
+void showCustomNameDialog(BuildContext context) {
+  showGeneralDialog(
+      context: context,
+      pageBuilder: (context, animation, secondaryAnimation) =>
+          CustomNameDialog(animation: animation));
+}
+
+class CustomNameDialog extends StatefulWidget {
+  final Animation<double> animation;
+
+  const CustomNameDialog({required this.animation, Key? key}) : super(key: key);
+
+  @override
+  State<CustomNameDialog> createState() => _CustomNameDialogState();
+}
+
+class _CustomNameDialogState extends State<CustomNameDialog> {
+  final TextEditingController _controller = TextEditingController();
+
+  @override
+  Widget build(BuildContext context) {
+    return ScaleTransition(
+      scale: CurvedAnimation(
+        parent: widget.animation,
+        curve: Curves.easeOutCubic,
+      ),
+      child: SimpleDialog(
+        title: const Text('Change name'),
+        children: [
+          TextField(
+            controller: _controller,
+            autofocus: true,
+            maxLength: 12,
+            maxLengthEnforcement: MaxLengthEnforcement.enforced,
+            textAlign: TextAlign.center,
+            textCapitalization: TextCapitalization.words,
+            textInputAction: TextInputAction.done,
+            onChanged: (value) {
+              context.read<SettingsController>().setPlayerName(value);
+            },
+            onSubmitted: (value) {
+              // Player tapped 'Submit'/'Done' on their keyboard.
+              Navigator.pop(context);
+            },
+          ),
+          TextButton(
+            onPressed: () => Navigator.pop(context),
+            child: const Text('Close'),
+          ),
+        ],
+      ),
+    );
+  }
+
+  @override
+  void didChangeDependencies() {
+    _controller.text = context.read<SettingsController>().playerName.value;
+    super.didChangeDependencies();
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+}