Fix two issues with missing whitespace when elements stack on top of each other while wrapping

Summary: Fixes T13476. Policy tags in object headers and "Visible To" controls in some dialog contexts may stack and wrap oddly. Improve spacing so they don't overlap visually when wrapping.

Test Plan: Viewed affected interfaces in narrow and wide windows.

Maniphest Tasks: T13476

Differential Revision: https://secure.phabricator.com/D20944