Make the superuser flag bypass TLD access checks

The --superuser command in the nomulus command-line tool should be
bypassing checks on whether the passed-in registrar client ID has access
to the TLD in question, but currently it is not.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=158974462

javatests/google/registry/flows/domain/DomainTransferRejectFlowTest.java

@@ -166,6 +166,19 @@ public class DomainTransferRejectFlowTest
     doSuccessfulTest("domain_transfer_reject.xml", "domain_transfer_reject_response.xml");
   }
 
+  @Test
+  public void testSuccess_superuserNotAuthorizedForTld() throws Exception {
+    persistResource(
+        Registrar.loadByClientId("TheRegistrar")
+            .asBuilder()
+            .setAllowedTlds(ImmutableSet.<String>of())
+            .build());
+    runFlowAssertResponse(
+        CommitMode.LIVE,
+        UserPrivileges.SUPERUSER,
+        readFile("domain_transfer_reject_response.xml"));
+  }
+
   @Test
   public void testFailure_badContactPassword() throws Exception {
     // Change the contact's password so it does not match the password in the file.