Allow users to swipe away stacked actions on mobile

Summary:
Ref T10004. This might be a little too funky or magical, but is probably not necessary too often and easier than doing new layout with the CSS.

Also make the desktop icons a little meatier.

Test Plan: Swiped things away on mobile. Clicked things away on desktop.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10004

Differential Revision: https://secure.phabricator.com/D14857