R1:2ce37034ad62

Move event host and times into event subheader

Summary:
Ref T11326. Show this information with a subheader instead of in properties.

Also, slightly simplify the list view.

Test Plan: {F1723539}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11326

Differential Revision: https://secure.phabricator.com/D16298