Add a Nomulus command to list Datastore operations

Command would be useful when checking the status of daily
backup jobs.

Only two modes are supported: list all operations, or list those
that started within the past period as specified by command line
option.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=229239783

java/google/registry/tools/RegistryToolComponent.java

@@ -97,6 +97,7 @@ interface RegistryToolComponent {
   void inject(GhostrydeCommand command);
   void inject(ImportDatastoreCommand command);
   void inject(ListCursorsCommand command);
+  void inject(ListDatastoreOperationsCommand command);
   void inject(LoadSnapshotCommand command);
   void inject(LockDomainCommand command);
   void inject(LoginCommand command);