[BREAKING CHANGE] MultiSelectWidget: Remove getSelectedItems and getSelectedItemsData
[BREAKING CHANGE] MultiSelectWidget: Remove getSelectedItems and getSelectedItemsData

Follows-up on Ic1be36b62f6c48c9f40feace009fe4ca3e7a8e3f

Bug: T76630
Change-Id: Ifd41ed61a10f62033796ecfa48375e5b234bbb38

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