* fix(keyboard-shortcuts): process Unidentified keys

When processing keyboard events for keyboard shortcuts,
if the value of an event's "key" attribute is "Unidentified",
the event should be further processed instead of the "key"
being returned to be mapped to a registered keyboard shortcut.
This occurs on edge, where question mark has the key
"Unidentified" but has the proper keyCode of 191.

* squash: add comment