The OAuth administrators group is documented on the OAuth extension page. The
mwoauthmanageconsumer right is required for Special:OAuthManageConsumers and listed on Special:ListGroupRights.
Authors of a "connected app" (something using OAuth) can propose their application on Special:OAuthConsumerRegistration/propose. An OAuth administrator can approve the application, it will then be listed on Special:OAuthListConsumers. Users can manage rights granted to their "connected apps" on Special:OAuthManageMyGrants.