BHV-13447: Added options to moon.Panels.pushPanels

This change allows you to specify an index to change to, once the panels have been added, and optionally not transition, but jump immediately to the target.

(Finally. This was originally created on March 1.)

Enyo-DCO-1.1-Signed-off-by: Blake Stephens <blake.stephens@lge.com>
I debated about whether to remove this option entirely, or leave this option in and just fix the other one. It seems like a useful feature to quickly and silently set the index immediately without transition, like during app initialization if you needed to load to a deeper state. Ex: Push 4 panels and start on the 4th panel, `pushPanels([1,2,3,4], {}, {setIndex: 3, transition: false)`