Analytics: Add sample network code

This doesn't seem to work. I'm not sure what I've done wrong with
google cloud run.

lib/analytics/network.dart

@@ -0,0 +1,55 @@
+import 'package:fixnum/fixnum.dart';
+import 'package:grpc/grpc.dart';
+
+import 'package:gitjournal/analytics/generated/analytics.pbgrpc.dart';
+import 'generated/analytics.pb.dart' as pb;
+
+Future<void> main(List<String> args) async {
+  final channel = ClientChannel(
+    'https://analyticsbackend-wetu2tkdpq-ew.a.run.app',
+    port: 8080,
+    options: ChannelOptions(
+      // credentials: const ChannelCredentials.insecure(),
+      credentials: const ChannelCredentials.secure(),
+      codecRegistry: CodecRegistry(codecs: const [
+        IdentityCodec(),
+        GzipCodec(),
+      ]),
+    ),
+  );
+
+  final stub = AnalyticsServiceClient(channel);
+  try {
+    var dt = DateTime.now().add(const Duration(days: -1));
+    var ev = pb.Event(
+      name: 'test',
+      date: Int64(dt.millisecondsSinceEpoch ~/ 1000),
+      params: {'a': 'hello'},
+      pseudoId: 'id',
+      userProperties: {'b': 'c'},
+      sessionID: 'session',
+    );
+
+    var request = AnalyticsMessage(
+      appId: 'io.gitjournal',
+      events: [ev],
+    );
+    print("Sending ${request.toDebugString()}");
+    var call = stub.sendData(
+      request,
+      options: CallOptions(timeout: const Duration(seconds: 10)),
+    );
+    call.headers.then((headers) {
+      print('Received header metadata: $headers');
+    });
+    call.trailers.then((trailers) {
+      print('Received trailer metadata: $trailers');
+    });
+    var response = await call;
+    print('Greeter client received: $response');
+  } catch (e) {
+    print('Caught error: $e');
+    return;
+  }
+  await channel.shutdown();
+}