MacOS: Mark our help menu as the macOS help menu

This gives it a nice search box for searching other menus

common/CocoaTools.h

@@ -19,6 +19,8 @@ namespace CocoaTools
 	void AddThemeChangeHandler(void* ctx, void(handler)(void* ctx));
 	/// Remove a handler previously added using AddThemeChangeHandler with the given context
 	void RemoveThemeChangeHandler(void* ctx);
+	/// Mark an NSMenu as the help menu
+	void MarkHelpMenu(void* menu);
 	/// Returns the bundle path.
 	std::optional<std::string> GetBundlePath();
 	/// Get the bundle path to the actual application without any translocation fun

common/CocoaTools.mm

@@ -143,6 +143,11 @@ void CocoaTools::RemoveThemeChangeHandler(void* ctx)
 	[s_themeChangeHandler removeCallback:ctx];
 }
 
+void CocoaTools::MarkHelpMenu(void* menu)
+{
+	[NSApp setHelpMenu:(__bridge NSMenu*)menu];
+}
+
 // MARK: - Sound playback
 
 bool Common::PlaySoundAsync(const char* path)

pcsx2-qt/MainWindow.cpp

@@ -151,6 +151,10 @@ void MainWindow::initialize()
 			ctx->updateTheme(); // Qt won't notice the style change without us touching the palette in some way
 		});
 	});
+	// The cocoa backing isn't initialized yet, delay this until stuff is set up with a `RunOnUIThread` call
+	QtHost::RunOnUIThread([this]{
+		CocoaTools::MarkHelpMenu(m_ui.menuHelp->toNSMenu());
+	});
 #endif
 	m_ui.setupUi(this);
 	setupAdditionalUi();