Add --set_current_tld_state to UpdateTldCommand

This feature would have been useful earlier when I was changing the TLD state on a sandbox TLD on-the-fly for testing purposes.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=128088578

javatests/google/registry/tools/CreateTldCommandTest.java

@@ -241,6 +241,16 @@ public class CreateTldCommandTest extends CommandTestCase<CreateTldCommand> {
     runCommandForced("--initial_tld_state=INVALID_STATE", "--roid_suffix=Q9JYB4C", "xn--q9jyb4c");
   }
 
+  @Test
+  public void testFailure_bothTldStateFlags() throws Exception {
+    thrown.expect(IllegalArgumentException.class);
+    DateTime now = DateTime.now(UTC);
+    runCommandForced(
+        String.format("--tld_state_transitions=%s=PREDELEGATION,%s=SUNRISE", now, now.plus(1)),
+        "--initial_tld_state=GENERAL_AVAILABILITY",
+        "xn--q9jyb4c");
+    }
+
   @Test
   public void testFailure_negativeInitialRenewBillingCost() throws Exception {
     thrown.expect(IllegalArgumentException.class);