Allow animating the elevation style (facebook#20739)

Summary:
Elevation should be supported by the native driver as it's a non-layout prop.
Pull Request resolved: facebook#20739

Differential Revision: D9468318

Pulled By: hramos

fbshipit-source-id: f8b8ca7536968ab8f6229c134fd169c321ccc651

Author: janicduplessis

Libraries/Animated/src/NativeAnimatedHelper.js

@@ -153,6 +153,7 @@ const STYLES_WHITELIST = {
   borderTopLeftRadius: true,
   borderTopRightRadius: true,
   borderTopStartRadius: true,
+  elevation: true,
   /* ios styles */
   shadowOpacity: true,
   shadowRadius: true,