Change feedback to use ITSR

Summary:
This isn't ready to release yet, it's still behind a GK so noone will see it.
There has been no styling applied to the popover so it looks bad but is fully functional.

What it also doesn't have yet:
* Get the prompt text from the API (including the predefined selectable comments)
* Check with the server whether it should pop up proactively, it's completely passive at the moment.

Reviewed By: passy

Differential Revision: D17206158

fbshipit-source-id: f1734f3d6bc555c860ebbaad7515d4675e1700cb

src/chrome/TitleBar.tsx

@@ -161,10 +161,7 @@ class TitleBar extends React.Component<Props, StateFromProps> {
         )}
         <Spacer />
         {config.showFlipperRating ? (
-          <RatingButton
-            rating={this.props.flipperRating}
-            onRatingChanged={this.props.setFlipperRating}
-          />
+          <RatingButton onRatingChanged={this.props.setFlipperRating} />
         ) : null}
         <Version>{this.props.version + (isProduction() ? '' : '-dev')}</Version>