Make simultaneous handlers always symmetric on iOS (#2800)

## Description

Current behavior only checks `simultaneousHandlers` field of the other
handler if there are none set in `simultaneousHandlers` of `this`
handler. This effectively makes it so the field is symmetrical only if
there are no simultaneous handlers declared on `this` handler.

This PR changes it, so that `simultaneousHandlers` of the other handler
are checked always if the checked handler tag is not present in this
handler's simultaneous list. This means that only one handler needs to
declare being simultaneous with the other one instead of declaring it
both ways.

apple/RNGestureHandler.m

@@ -482,7 +482,9 @@ - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
           return YES;
         }
       }
-    } else if (handler->_simultaneousHandlers) {
+    }
+
+    if (handler->_simultaneousHandlers) {
       for (NSNumber *handlerTag in handler->_simultaneousHandlers) {
         if ([self.tag isEqual:handlerTag]) {
           return YES;