Fix issue with setting shadow node state data after scrolling programmatically

Summary:
This issue is found when investigating T101563978 with IOS platform. When animation is off, the x position measurement is off after `scrollToItem` is called.

The android fix is checked in at D31492685 (1a9e2d5). For IOS, the correct state data is updated only for animated cases, but not for instant scroll cases. This diff unified them.

Changelog
[IOS][Fixed] Fixed an edge case when scroll to item/index is called without animation, the offset position is not updated. This caused the measurement of the position to be wrong.

Reviewed By: sammy-SC

Differential Revision: D31564169

fbshipit-source-id: 89f47d8054afb03c2ace1d595163b160e5bb2036

Author: ryancat

React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm

@@ -498,6 +498,11 @@ - (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
 }
 
 - (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView
+{
+  [self _handleFinishedScrolling:scrollView];
+}
+
+- (void)_handleFinishedScrolling:(UIScrollView *)scrollView
 {
   [self _forceDispatchNextScrollEvent];
   [self scrollViewDidScroll:scrollView];
@@ -710,6 +715,12 @@ - (void)scrollToOffset:(CGPoint)offset animated:(BOOL)animated
   }
 
   [_scrollView setContentOffset:offset animated:animated];
+
+  if (!animated) {
+    // When not animated, the expected workflow in ``scrollViewDidEndScrollingAnimation`` after scrolling is not going
+    // to get triggered. We will need to manually execute here.
+    [self _handleFinishedScrolling:_scrollView];
+  }
 }
 
 - (void)zoomToRect:(CGRect)rect animated:(BOOL)animated