Make drag-and-drop to upload files work on any Home dashboard, not just "Magic Home"

Summary: Ref T12174. Drag-and-drop-to-upload requires some stuff in the document. Put that stuff on all the content pages (currently: dashboards, magic home), not just the builtin home.

Test Plan:

• Dragged-and-dropped onto a Home dashbboard to upload.
• Viewed, and dragged-and-dropped onto "builtin home" to upload.
• Dragged onto "Edit Menu" for home, no upload.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12174

Differential Revision: https://secure.phabricator.com/D17307