Added Google Maps sample code (#1671)

* Added Google Maps sample code

* Updated per @domesticmouse review

* Updated dependabot and pubspec for Dart 2.19

google_maps/lib/main.dart

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2019 Google LLC
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import 'package:flutter/material.dart';
+import 'package:google_maps_flutter/google_maps_flutter.dart';
+
+void main() => runApp(const MyApp());
+
+class MyApp extends StatefulWidget {
+  const MyApp({super.key});
+
+  @override
+  State<MyApp> createState() => _MyAppState();
+}
+
+class _MyAppState extends State<MyApp> {
+  late GoogleMapController mapController;
+
+  final LatLng _center = const LatLng(-33.86, 151.20);
+
+  void _onMapCreated(GoogleMapController controller) {
+    mapController = controller;
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      home: Scaffold(
+        appBar: AppBar(
+          title: const Text('Sydney'),
+          backgroundColor: Colors.green[700],
+        ),
+        body: GoogleMap(
+            onMapCreated: _onMapCreated,
+            initialCameraPosition: CameraPosition(
+              target: _center,
+              zoom: 11.0,
+            ),
+            markers: {
+              // ignore: prefer_const_constructors
+              Marker(
+                markerId: const MarkerId('Sydney'),
+                position: const LatLng(-33.86, 151.20),
+              )
+            }),
+      ),
+    );
+  }
+}