Keys for the global keyboard listener of PlayControlNode should be customizable

[jessegreenberg]

Currently, the only way to change the global hotkey listener added to the PlayControlNode is to remove it entirely with includeGlobalHotKey, a boolean option that prevents the listener from being added.

It would be much better if we could customize the hotkeys that fire the global key listener. This should be a general design pattern for hot keys in common code. It is OK for there to be a default hot key, but it should be customizable.

Relevant Slack conversation:

Putting the hot key in PlayControlButton is problematic. What if I have 2 play/pause buttons on a screen, for controlling different things?   PlayControlButton has options.includeGlobalHotKey only, so you’re out of luck.

Jesse Greenberg  2:36 PM
Wouldn't that option cover it? If you had two you would probably want to disable the hotkey.

Chris Malley  2:37 PM
Not at all.  PlayControlButton is a reusable UI component, designed to be used in many contexts.  Assuming that there is only 1 hot key is also assuming that there is only 1 context.
2:38
It’s OK for reusable UI components to have default hot keys. But they should not be limited to only 1 hot key.

Jesse Greenberg  2:40 PM
OK, gotchya. We can make the hotkeys for that listener customizable.

Chris Malley  2:40 PM
That should be the general pattern for anything in common code.

[zepumph]

Subset of phetsims/scenery#1298