Add x-undo for operations (#178)

* Load undo methods

* Regenerate client from commit 87f1f19 of spec repo

Co-authored-by: Jiri Kuncar <jiri.kuncar@gmail.com>
Co-authored-by: api-clients-generation-pipeline[bot] <54105614+api-clients-generation-pipeline[bot]@users.noreply.github.com>
Co-authored-by: ci.datadog-api-spec <packages@datadoghq.com>

Author: 3 people

.apigentools-info

@@ -4,13 +4,13 @@
     "spec_versions": {
         "v1": {
             "apigentools_version": "1.3.0",
-            "regenerated": "2020-12-01 11:05:09.268295",
-            "spec_repo_commit": "34f647e"
+            "regenerated": "2020-12-01 16:27:08.825574",
+            "spec_repo_commit": "87f1f19"
         },
         "v2": {
             "apigentools_version": "1.3.0",
-            "regenerated": "2020-12-01 11:05:19.520168",
-            "spec_repo_commit": "34f647e"
+            "regenerated": "2020-12-01 16:27:19.540981",
+            "spec_repo_commit": "87f1f19"
         }
     }
 }