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/host/HostUpdateFlow.java

@@ -47,6 +47,8 @@ import org.joda.time.Duration;
 
 import java.util.Objects;
 
+import javax.inject.Inject;
+
 /**
  * An EPP flow that updates a host resource.
  *
@@ -72,6 +74,8 @@ public class HostUpdateFlow extends ResourceUpdateFlow<HostResource, Builder, Up
   private String newHostName;
   private boolean isHostRename;
 
+  @Inject HostUpdateFlow() {}
+
   @Override
   protected void initResourceCreateOrMutateFlow() throws EppException {
     String suppliedNewHostName = command.getInnerChange().getFullyQualifiedHostName();