Marker directive for the keyboard-shortcut hint position inside a
[cngxMenuItem]. Applies cngx-menu-item__kbd and defaults the host
to aria-hidden="true" - the visual hint duplicates the underlying
accelerator already wired to the consumer's command, AT readout of the
hint would just repeat the label. Typically placed on a <kbd>.
Override with [attr.aria-hidden]="null" if the hint is a consumer's
primary affordance.