Apply a TYPE_CREATE transaction when importing events to improve strings in timeline

Summary: Ref T10747. This turns on the newer EditEngine behavior so we get a nice "X created this event." transaction, instead of an "X renamed this from <nothing> to Event Name."

Test Plan: Imported an event, saw a nice timeline.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10747

Differential Revision: https://secure.phabricator.com/D16771