Issue 12353 fix detach context menu strip memory leak (dotnet#12399)

* Removing reference to ContextMenuStrip when dispose control

* Merge 'main' to current branch

* Detach ContextMenuStrip from control when executing Dispose

* Use pattern matching for judge variable menu

src/System.Windows.Forms/src/System/Windows/Forms/Control.cs

@@ -4694,6 +4694,12 @@ protected override void Dispose(bool disposing)
             }
         }
 
+        // Unsubscribes from the Disposed event of the ContextMenuStrip.
+        if (ContextMenuStrip is ContextMenuStrip menu)
+        {
+            menu.Disposed -= DetachContextMenuStrip;
+        }
+
         ReflectParent = null;
 
         if (disposing)