Add aria-label to toolbar icon buttons
Add aria-label to toolbar icon buttons

Helps improve screen reader output for icon buttons.

fullcalendar/fullcalendar,arshaw/fullcalendar,kleisauke/fullcalendar,kleisauke/fullcalendar,arshaw/fullcalendar,oleg-babintsev/fullcalendar,fullcalendar/fullcalendar,fullcalendar/fullcalendar,fullcalendar/fullcalendar,oleg-babintsev/fullcalendar,kleisauke/fullcalendar,arshaw/fullcalendar,kleisauke/fullcalendar,arshaw/fullcalendar,oleg-babintsev/fullcalendar