macOS: Add open files to system recent files

Completes the TODO in GHOST_SystemPathsCocoa::addToSystemRecentFiles
Also renames the filename parameter to the more appropriate filepath.

The recently opened/saved file will now also show up in:
- Blender Dock icon > Right click.
- Three finger swipe down in Open Blender i.e., App Expose

Based on a earlier contribution by @jenkm.

Pull Request: https://projects.blender.org/blender/blender/pulls/107174

source/blender/windowmanager/intern/wm_files.cc

@@ -1584,7 +1584,7 @@ static void wm_history_file_update(void)
     /* Write current file to #BLENDER_HISTORY_FILE. */
     wm_history_file_write();
 
-    /* also update most recent files on System */
+    /* Also update most recent files on system. */
     GHOST_addToSystemRecentFiles(blendfile_path);
   }
 }