Add Widgets local task to /admin/content

Panopoly has a discoverability problem. As a content creator, if I add a custom content widget to a page how do I direct another person to find that widget, they would have a heck of time finding it if they didn't have deep knowledge of the system. The answer: /admin/structure/fieldable-panels-panes/manage/text (Yeesh)

Why can't they find content that was created on the content page (/admin/content)? That is where other content is found.

If we had a tab on the content page that displayed a full list of Panopoly widgets that have been instantiated / created that would make it easier to find, sure but we would also need a bit more context than regular content. We would need to know what page it was on, and have a link that you could navigate to to see the widget in action. The actions we took on this page should invoke the appripriate logic of disassoiating the widget from the page(s) it was assigned and delete the widget's instance from the system.

I also think this would make it easier for people to find widgets that they want to reuse (and maybe someday clone).

Next Steps:

1. Create a view that displays existing fieldable panel panes of any type
2. Make the view include: name of FFP, link(s) to page(s) it's used on,
3. Allow the view to include a set of contextual actions: edit / delete
4. Maybe some bulk actions

What do you think?