Make _CssStateMixin use dojo/touch events rather than "touchstart" and "touchend" so that  (in particular the active state) will work on Surface.   Fixes #16823.

Also add new press and release synthetic events to dijit/a11yclick, representing either mousedown/mouseup, touchstart/touchend, or keydown/keyup corresponding to a click event.  Use new dijit/a11yclick events in _CssStateMixin to provide visual feedback during keyboard "clicks".    For non-IE platforms this moves the listener from the capturing phase to the bubbling phase, which seems to be working OK (especially considering that IE's worked this way from the beginning), but there might be some stopPropagation() calls somewhere the need to be removed.  Fixes #8709 !strict.

This is also in preparation to convert Tree to use dijit/a11yclick.  Refs #16819.