Move update charm to new UX - first iteration

This branch moves the update charm functionality out of the service overview viewlet and into its own viewlet that can be loaded on demand, rather than on opening the inspector.  Note that there are follow-up style branches, and may be follow-up technical branches as well - first iteration.
I know this is temporary as we work towards the change/destroy buttons being side by side as in the design, but in my head it makes more sense to see the upgrade option before destroy in a vertical list.