* Make LookupBase an abc with required methods (run()) marked as an
abstractmethod
* Mark methods that don't use self as @staticmethod
* Document how to implement the run method of a lookup plugin.
Fixes bugs related to creating Templar() objects on the fly, where
the shared loader objects (serialized to TaskExecutor) aren't used
so information loaded into plugin loaders after forking is lost.
Fixes#11815
Toshio Kuratomi
James Cammarata
Brian Coca