Add option --non_live_versions to set_num_instances command

This commit introduced a new flag to enable SetNumInstancesCommand to
be able to set the number of instances for all non-live versions for
a given service or for all deployed services.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=222826003

java/google/registry/config/files/default-config.yaml

@@ -282,6 +282,11 @@ credentialOAuth:
     - https://www.googleapis.com/auth/admin.directory.group
     # View and manage group settings in Group Settings API.
     - https://www.googleapis.com/auth/apps.groups.settings
+  # OAuth scopes required for accessing App Engine Admin API using the
+  # AppIdentityCredential.
+  appEngineAdminApiCredentialOauthScopes:
+    # View and manage your applications deployed on Google App Engine
+    - https://www.googleapis.com/auth/appengine.admin
 
 
 icannReporting: