Explicitly hide mode in showbinds menu

[CatsDeservePets]

• Follow-up to Hide mode when listing single-mode binds #2226

Instead of checking for the amount of dictionaries passed to listBinds, I decided to introduce the parameter showMode to explicitly control whether mode should be shown.

It is only hidden when displaying the showbinds menu. Executing the commands maps, nmaps, vmaps and cmaps still displays the mode as it did before.