Add `get_accessid_by_email` to DirectoryService::Client interface

[ajkiessl]

Much of this (https://github.com/psu-libraries/etda_workflow/blob/main/app/models/directory_service.rb) code is repeated in the DirectoryService client. It would probably be better to just add the get_accessid_by_email code to the DirectoryService client and remove what's in ETDA.