Add assertion to _CupertinoSwitchRenderObjectWidget, otherwise it is confusing why updateRenderObject omits state update (#112044)

diff --git a/packages/flutter/lib/src/cupertino/switch.dart b/packages/flutter/lib/src/cupertino/switch.dart
index 550c953..1433289 100644
--- a/packages/flutter/lib/src/cupertino/switch.dart
+++ b/packages/flutter/lib/src/cupertino/switch.dart
@@ -378,6 +378,7 @@
 
   @override
   void updateRenderObject(BuildContext context, _RenderCupertinoSwitch renderObject) {
+    assert(renderObject._state == state);
     renderObject
       ..value = value
       ..activeColor = activeColor