Add end-to-end code to run Beam template from App Engine

This serves as proof-of-concept to verify we can use Beam for our invoice generation use case. Namely, it checks that we can:
- Deploy a Beam template to GCS
- Read from Bigquery within the template
- Run the template from App Engine

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=175755390

java/google/registry/billing/BillingModule.java

@@ -0,0 +1,50 @@
+// Copyright 2017 The Nomulus Authors. All Rights Reserved.
+//
+// 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
+//
+//     http://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.
+
+package google.registry.billing;
+
+import com.google.api.client.googleapis.extensions.appengine.auth.oauth2.AppIdentityCredential;
+import com.google.api.client.http.HttpTransport;
+import com.google.api.client.json.JsonFactory;
+import com.google.api.services.dataflow.Dataflow;
+import com.google.common.base.Function;
+import com.google.common.collect.ImmutableSet;
+import dagger.Module;
+import dagger.Provides;
+import google.registry.config.RegistryConfig.Config;
+import java.util.Set;
+
+/** Module for dependencies required by monthly billing actions. */
+@Module
+public final class BillingModule {
+
+  private static final String CLOUD_PLATFORM_SCOPE =
+      "https://www.googleapis.com/auth/cloud-platform";
+
+  /** Constructs a {@link Dataflow} API client with default settings. */
+  @Provides
+  static Dataflow provideDataflow(
+      @Config("projectId") String projectId,
+      HttpTransport transport,
+      JsonFactory jsonFactory,
+      Function<Set<String>, AppIdentityCredential> appIdentityCredentialFunc) {
+
+    return new Dataflow.Builder(
+            transport,
+            jsonFactory,
+            appIdentityCredentialFunc.apply(ImmutableSet.of(CLOUD_PLATFORM_SCOPE)))
+        .setApplicationName(String.format("%s billing", projectId))
+        .build();
+  }
+}