macOS: non-native fullscreen should not hide menu on fullscreen space

Fixes #7075

We have to use private APIs for this, I couldn't find a reliable way
otherwise.

macos/Sources/Helpers/NSWindow+Extension.swift

@@ -0,0 +1,8 @@
+import AppKit
+
+extension NSWindow {
+    /// Get the CGWindowID type for the window (used for low level CoreGraphics APIs).
+    var cgWindowId: CGWindowID {
+        CGWindowID(windowNumber)
+    }
+}