Add alt-input support for time-based FireListeners

[jessegreenberg]

We will need support for buttons that have fireOnHold and related time-based intervals like fireOnHoldDelay and fireOnHoldInterval. Currently these are supported by the PDOM implementation in PressListener because the firing happens in response to single click events. This was discussed in detail in #939 and #931. The result of those issues is that we would like to do the following:

• Add a way to opt-out of the click listener in PressListener.
• Create a listener that fires in response to keydown/keyup events instead.
• Time-based buttons throughout PhET should use this new listener and change their PDOM representation from button to role=application so that they receive the keydown and keyup events.

We will work on this the next time we encounter a sim with a time-based button.

[zepumph]

Probably good to mention #1298 to track alt input generally.

[zepumph]

Very related to the sun button support needed in phetsims/sun#857