Publish web_embedding (#1777)

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.

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Co-authored-by: Mark Thompson
<2554588+MarkTechson@users.noreply.github.com>
Co-authored-by: David Iglesias <ditman@gmail.com>

Co-authored-by: Mark Thompson <2554588+MarkTechson@users.noreply.github.com>
Co-authored-by: David Iglesias <ditman@gmail.com>

web_embedding/ng-flutter/flutter/lib/pages/counter.dart

@@ -0,0 +1,47 @@
+import 'package:flutter/material.dart';
+
+class CounterDemo extends StatefulWidget {
+  final ValueNotifier<int> counter;
+
+  const CounterDemo({
+    super.key,
+    required this.counter,
+  });
+
+  @override
+  State<CounterDemo> createState() => _CounterDemoState();
+}
+
+class _CounterDemoState extends State<CounterDemo> {
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
+        title: const Text('Counter'),
+      ),
+      body: Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: <Widget>[
+            const Text(
+              'You have pushed the button this many times:',
+            ),
+            ValueListenableBuilder(
+              valueListenable: widget.counter, 
+              builder: (context, value, child) => Text(
+                '$value',
+                style: Theme.of(context).textTheme.headlineMedium,
+              ),
+            ),
+          ],
+        ),
+      ),
+      floatingActionButton: FloatingActionButton(
+        onPressed: () { widget.counter.value++; },
+        tooltip: 'Increment',
+        child: const Icon(Icons.add),
+      ),
+    );
+  }
+}