Convert AppEngineConnection to use HttpTransport

Make AppEngineConnection use HttpTransport through HttpRequestFactory and
create factory factories for localhost and HTTPOverRPC.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=143680257

java/google/registry/tools/RegistryToolComponent.java

@@ -26,6 +26,7 @@ import google.registry.request.Modules.Jackson2Module;
 import google.registry.request.Modules.URLFetchServiceModule;
 import google.registry.util.SystemClock.SystemClockModule;
 import google.registry.util.SystemSleeper.SystemSleeperModule;
+import javax.inject.Singleton;
 
 /**
  * Dagger component for Registry Tool.
@@ -33,8 +34,10 @@ import google.registry.util.SystemSleeper.SystemSleeperModule;
  * <p>Any command class with {@code @Inject} fields <i>must</i> be listed as a method here.
  * Otherwise {@link RegistryCli} will not be able to populate those fields after its instantiation.
  */
+@Singleton
 @Component(
   modules = {
+    AppEngineConnectionFlagsModule.class,
     ConfigModule.class,
     DatastoreServiceModule.class,
     CloudDnsWriterModule.class,
@@ -47,6 +50,9 @@ import google.registry.util.SystemSleeper.SystemSleeperModule;
     SystemSleeperModule.class,
     URLFetchServiceModule.class,
     VoidDnsWriterModule.class,
+  },
+  dependencies = {
+    HttpRequestFactoryComponent.class,
   }
 )
 interface RegistryToolComponent {
@@ -68,4 +74,6 @@ interface RegistryToolComponent {
   void inject(UpdateTldCommand command);
   void inject(ValidateEscrowDepositCommand command);
   void inject(WhoisQueryCommand command);
+
+  AppEngineConnection appEngineConnection();
 }