Multiple pick up sounds trigger unexpectedly

[samreid]

Discovered in phetsims/faradays-electromagnetic-lab#103, we found that when keyboard dragging an item such as the Projectile Data Lab stopwatch or the Faradays Electromagnetic Lab field meter node, there is a sound when you press an arrow key, indicating the pick up. When you release the key there is a drop sound. That is all working well.

But if you press multiple keys, for instance, to move something at a diagonal, there is an unexpected sound effect. For instance:

1. Tab to select the Field Meter Node in screen 1 of FEL.
2. Press the right arrow to start dragging to the right
3. While dragging to the right, tap the down arrow repeatedly.

The effect is that you will hear multiple pickup sounds even though the tool is already picked up.

Likewise, if you hold down the right arrow and press the left arrow, the object will stop moving and you will hear another "pick up" sound.

I reached out to @jessegreenberg and he said this was unexpected and should be addressed. He indicated the problem may lie in this code:

scenery/js/listeners/KeyboardDragListener.ts

Lines 322 to 342 in a4abda7

	// If there are no movement keys down, attach a listener to the Pointer that will tell the AnimatedPanZoomListener
	// to keep this Node in view
	if ( !this.movementKeysDown && KeyboardUtils.isMovementKey( event.domEvent ) ) {
	assert && assert( this._pointer === null, 'We should have cleared the Pointer reference by now.' );
	this._pointer = event.pointer as PDOMPointer;
	event.pointer.addInputListener( this._pointerListener, true );
	this.isPressedProperty.value = true;
	}
	// update the key state
	this.keyState.push( {
	keyDown: true,
	key: key!,
	timeDown: 0 // in ms
	} );
	if ( this._start ) {
	if ( this.movementKeysDown ) {
	this._start( event );
	}
	}

This means the "drag started" sequence is getting called more than once, which may be causing other side effects. @jessegreenberg can you please review and advise?

[jessegreenberg]

This was fixed during #1570, the start callback only calls at the start of the operation instead of every key press. Closing.