Fix MacOS menu bar & dock stop appearing after closing sub-window

When the progress dialog task for saving a scene ends, or when closing the "Open project" dialog, the DisplayServerMacOS::update_presentation_mode() method now restores those fullscreen functionalities with the flags NSApplicationPresentationAutoHideMenuBar and NSApplicationPresentationAutoHideDock, whereas before it would reset to NSApplicationPresentationDefault, which didn't allow that.

Fixes #86495

platform/macos/display_server_macos.mm

@@ -2084,12 +2084,21 @@
 }
 
 void DisplayServerMacOS::update_presentation_mode() {
+	bool has_fs_windows = false;
 	for (const KeyValue<WindowID, WindowData> &wd : windows) {
-		if (wd.value.fullscreen && wd.value.exclusive_fullscreen) {
-			return;
+		if (wd.value.fullscreen) {
+			if (wd.value.exclusive_fullscreen) {
+				return;
+			} else {
+				has_fs_windows = true;
+			}
 		}
 	}
-	[NSApp setPresentationOptions:NSApplicationPresentationDefault];
+	if (has_fs_windows) {
+		[NSApp setPresentationOptions:NSApplicationPresentationAutoHideMenuBar | NSApplicationPresentationAutoHideDock | NSApplicationPresentationFullScreen];
+	} else {
+		[NSApp setPresentationOptions:NSApplicationPresentationDefault];
+	}
 }
 
 void DisplayServerMacOS::window_set_min_size(const Size2i p_size, WindowID p_window) {