Summary:
Changelog: [Internal]
Introduce native command `setNativeRefreshing`, it has the word Native in order to avoid name conflict with setRefreshing in Android implementation. Even this component is iOS only, it would make it easier to merge them in the future.
Introduce `RCTRefreshableProtocol` and make `RCTRefreshControl` and `RCTPullToRefreshViewComponentView` to conform to the protocol so view manager can forward command to both, Paper and Fabric component.
Reviewed By: mmmulani
Differential Revision: D18475804
fbshipit-source-id: 4c19225784efc931b7b8f2d2671cc839bce429bf