Update property to read when handling keyboard events

[Gregg8]

When determining what key was pressed in keyboard event handlers, we examine various properties:

• which is used by drop-down, input-text and typeahead
• keyCode is used by input-time

Both of these are now deprecated, so they should all be switched to use the key property - info

Thanks to: https://github.com/Day8/re-frame-10x/issues/231

[Frozenlock]

Some additional info, in case it would be useful:

keyCode is supported by all browsers. (According to caniuse.com)

key not as much. https://caniuse.com/#search=keyboardevent.key