Add delete_host nomulus tool command

This is needed to delete an invalid host resulting from a previous bug.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=154757425

java/google/registry/tools/RegistryTool.java

@@ -50,6 +50,7 @@ public final class RegistryTool {
           .put("delete_credit", DeleteCreditCommand.class)
           .put("delete_domain", DeleteDomainCommand.class)
           .put("delete_entity", DeleteEntityCommand.class)
+          .put("delete_host", DeleteHostCommand.class)
           .put("delete_premium_list", DeletePremiumListCommand.class)
           .put("delete_reserved_list", DeleteReservedListCommand.class)
           .put("delete_tld", DeleteTldCommand.class)