Dagger, meet Flows. Flows, meet Dagger.

Daggerizes all of the EPP flows. This does not change anything yet
about the flows themselves, just how they are invoked, but after
this CL it's safe to @Inject things into flow classes.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=125382478

java/google/registry/flows/domain/DomainTransferApproveFlow.java

@@ -45,6 +45,8 @@ import google.registry.model.transfer.TransferData;
 
 import org.joda.time.DateTime;
 
+import javax.inject.Inject;
+
 /**
  * An EPP flow that approves a pending transfer on a {@link DomainResource}.
  *
@@ -60,6 +62,8 @@ import org.joda.time.DateTime;
 public class DomainTransferApproveFlow extends
     ResourceTransferApproveFlow<DomainResource, Builder, Transfer> {
 
+  @Inject DomainTransferApproveFlow() {}
+
   @Override
   protected void verifyOwnedResourcePendingTransferMutationAllowed() throws EppException {
     checkAllowedAccessToTld(getAllowedTlds(), existingResource.getTld());