fix(whats-new): Allow "What's New" modal to appear

[TSenter]

The did-insert modifier that the nrg-new-features component passes to the nrg-modal component is never attached to a DOM element, since no passed-in attributes to nrg-modal components are used anywhere. This worked in previous Ember versions since all Ember components are wrapped in a div by default, which is also where attributes were placed. Therefore, the modifier was placed on the div wrapping the modal component; this div no longer exists.