Convert "Created By" and "Invited" inputs in Calendar search to use PhabricatorPeopleUserFunctionDatasource
Summary: Closes T8046, Convert "Created By" and "Invited" inputs in Calendar search to use PhabricatorPeopleUserFunctionDatasource
Test Plan: Calendar → Advanced Search, search for "members:Calendar", created by and invited. Should autofill and search correctly.
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: epriestley, Korvin
Maniphest Tasks: T8046
Differential Revision: https://secure.phabricator.com/D13311