add settings to application menu

The option to change the settings is currently only available from the bottom of the links on the left-hand side of the application.

It would be helpful if there was also an option to reach this dialog from the application menu bar, as it's currently the only feature without a matching menu button.

Start by locating the application menu bar implementation and the existing settings dialog or left-side settings link. Trace how the current link opens the dialog, then add a matching menu entry and verify that it reaches the same settings dialog.

Written by the indexing model from the issue text.