MenuTagMultiselectWidget: Add test for 'selected' config option
MenuTagMultiselectWidget: Add test for 'selected' config option

Follow-up to 40713e0f17fac2b29550bb4384e30f247460b434.

Bug: T164750
Change-Id: Ic53010616f83661f45f7da535052919df4a6ad3a

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui