Add explicit dismiss button to feedback prompt
Add explicit dismiss button to feedback prompt

Summary:
You can already click the star icon in the title bar to dismiss, but according to feedback this isn't obvious: https://our.intern.facebook.com/intern/itsr?start_date=1561849200&end_date=1570402800&tab=4&all_tools=true

So adding an explicit dismiss button.

Reviewed By: passy

Differential Revision: D17788570

fbshipit-source-id: b0995e5abdaafc5bd6f93edb27dad703c81b8f2b

facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper