[Storage] Bucket Lock (#3727)

* [Storage] Replay GCS Bucket Lock (#3645)

* Add support for defaultEventBasedHold

* Add support for Blob eventBasedHold

* Add support for blob temporary holds

* Remove Beta launch annotations for CMEK

* Add support for lockRetentionPolicy and RetentionPolicy

* Update FakeStorageRPC

* codacy-bot review fix (final only)

* Update getRetentionPolicyIsLocked() -> retentionPolicyIsLocked() and misc.

* Address comments

* Address comments

* Address comments.

* Small nits

* Fix additional comments

* [Storage] Bucket lock samples and bug fixes. (#3709)

* Fix issue in tests, write bucket lock samples, and resolve issue in client library

* Update documentation around Boolean returns to clarify different return caes.

* Fix broken unit test

* Address feedback

* Fix typo in comments

Author: frankyn

java-storage-nio/google-cloud-nio/src/main/java/com/google/cloud/storage/contrib/nio/testing/FakeStorageRpc.java

@@ -65,6 +65,7 @@
  *   <li>createBatch
  *   <li>checksums, etags
  *   <li>IAM operations</li>
+ *   <li>BucketLock operations</li>
  *   </ul>
  * </ul>
  */
@@ -520,6 +521,11 @@ public Notification createNotification(String bucket, Notification notification)
     throw new UnsupportedOperationException();
   }
 
+  @Override
+  public Bucket lockRetentionPolicy(Bucket bucket, Map<Option, ?> options) {
+    throw new UnsupportedOperationException();
+  }
+
   @Override
   public ServiceAccount getServiceAccount(String projectId) {
     return null;