Summary: Depends on D19249. Ref T13109. Add timing information to the `PushEvent`: - `writeWait`: Time spent waiting for a write lock. - `readWait`: Time spent waiting for a read lock. - `hostWait`: Roughly, total time spent on the leaf node. The primary goal here is to see if `readWait` is meaningful in the wild. If it is, that motivates smarter routing, and the value of smarter routing can be demonstrated by looking for a reduction in read wait times. Test Plan: Pushed some stuff, saw reasonable timing values in the table. Saw timing information in "Export Data". Maniphest Tasks: T13109 Differential Revision: https://secure.phabricator.com/D19250