InputWidget: Remove the 'setAccessKey' method
InputWidget: Remove the 'setAccessKey' method

The implementation in OO.ui.AccessKeyedElement works for inputs too.

Follow-up to f0c1f434241b6d538d89c770634b8917690ec5da.

Change-Id: Iaa723e91c0a346ff6674584873aafd331ffc57ef

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