Add domain_lock nomulus command

This command is used by registry operators to apply registry locks to
domain names.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=176549874

java/google/registry/tools/RegistryTool.java

@@ -95,6 +95,7 @@ public final class RegistryTool {
           .put("list_tlds", ListTldsCommand.class)
           .put("load_snapshot", LoadSnapshotCommand.class)
           .put("load_test", LoadTestCommand.class)
+          .put("lock_domain", LockDomainCommand.class)
           .put("login", LoginCommand.class)
           .put("logout", LogoutCommand.class)
           .put("make_billing_tables", MakeBillingTablesCommand.class)