Show responsible package & link to its settings

[saizai]

Sometimes multiple packages provide very similar (or identically named) items. Or you forget what you installed that provides this and don't want it any more.

So, always show (right-aligned) the package responsible for this entry, and a gear button linking to its settings page.

crosslink: atom/encoding-selector#60

[maxbrunsfeld]

This issue was moved to atom/atom#18259