keypress page turn/hotkeys

[psalaets]

• left arrow fires secondary action
• right arrow fires primary action
• I feel like spacebar should also fire primary action

[psalaets]

@cbleslie hmm default browser behavior for spacebar is page down. Should we override that?

[cbleslie]

@psalaets For now, I think it's okay. Space/Enter at the OS level to activate buttons. So in theory, we can have it activate the "button". Easy to reverse if it hurts users.

[psalaets]

hold off until we figure out how this affects a11y