Fix buttons property value for non-hoverable pointers

Summary:
Changelog: [iOS][Internal] - Fix buttons property value for non-hoverable pointers

The previous diff ensured that on iOS you could run through the entirety of the non-hoverable pointer event attributes test but that also revealed some failing tests related to the `buttons` property when using a non-hoverable pointer. This diff fixes that by ensuring that we only forward the result of the `buttonMask` to `buttons` when the pointer is a mouse, and assume that it is an emulated left click otherwise.

Reviewed By: lunaleaps

Differential Revision: D38914239

fbshipit-source-id: c573e934d0e9c0ac2af4945dc5360840ddc87d4d

Author: vincentriemer

React/Fabric/RCTSurfaceTouchHandler.mm

@@ -349,7 +349,16 @@ static PointerEvent CreatePointerEventFromActiveTouch(ActiveTouch activeTouch, R
     event.button = activeTouch.button;
   }
 
-  event.buttons = ButtonMaskToButtons(activeTouch.buttonMask);
+  event.buttons = 1;
+  if (@available(iOS 13.4, *)) {
+    if (activeTouch.touchType == UITouchTypeIndirectPointer) {
+      // Indirect pointers are the only situations where buttonMask is "accurate"
+      // so we override the assumed "left click" button value when those type of
+      // events are recieved
+      event.buttons = ButtonMaskToButtons(activeTouch.buttonMask);
+    }
+  }
+
   UpdatePointerEventModifierFlags(event, activeTouch.modifierFlags);
 
   // UIEvent's button mask for touch end events still marks the button as down