Fix borders on “Pair with observers” button
Fix borders on “Pair with observers” button

Because this file wasn’t importing the “direction” sass helper, it
would silently just render it as literal text 
eg:
.page-action-list #pairing-code button {
  display: block;
  …
  border-direction(left): none;
  border-direction(right): none;
  …
}

Before: https://cl.ly/87a612c10374
After: https://cl.ly/824ff92491e1

Test plan:
* go to courses/x/users/y 
* make sure “pair with observer” button looks right

Change-Id: I97ba9a2587462dd0c364149ffbb2154ceb79d653
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/214139
Tested-by: Jenkins
Reviewed-by: Ed Schiebel <0ca8a83847a5889cf05cb219c0ab09f6b646243b@instructure.com>
QA-Review: Ryan Shaw <ea3cd978650417470535f3a4725b6b5042a6ab59@instructure.com>
Product-Review: Ryan Shaw <ea3cd978650417470535f3a4725b6b5042a6ab59@instructure.com>

instructure/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,instructure/canvas-lms