[add] Allow style scrollbarWidth 'thin' value

Close #1499

Author: necolas

packages/react-native-web/src/exports/View/types.js

@@ -49,7 +49,7 @@ export type ViewStyle = {
   overscrollBehavior?: OverscrollBehaviorValue,
   overscrollBehaviorX?: OverscrollBehaviorValue,
   overscrollBehaviorY?: OverscrollBehaviorValue,
-  scrollbarWidth?: 'auto' | 'none',
+  scrollbarWidth?: 'auto' | 'none' | 'thin',
   scrollSnapAlign?: string,
   scrollSnapType?: string,
   WebkitMaskImage?: string,