Rather than having to 'unregister' both 'RHOST' and 'RHOSTS' for modules using a network-connecting mixin, this allows just unregistering one option by exposing the alias key lookup to the module options library and allowing it to remove the datastore options for the module from validation.
Noted while testing #11108 that the module's unregister options were incomplete, and there were a few more like it. This allows modules operating in this style to work without modifications.
Dean Welch