Add very basic "quick create" menu
Summary:
Ref T3623. This is like a pre-v0, in that it doesn't have a dropdown yet.
Clicking the button takes you to a page which can serve as a right click / mobile / edit target in the long run, but is obviously not great for desktop use. I'll add the dropdown in the next iteration.
Test Plan: {F105631}
Reviewers: chad, btrahan
Reviewed By: chad
CC: aran
Maniphest Tasks: T3623
Differential Revision: https://secure.phabricator.com/D8088