bookmark button should retain focus

fixes CNVS-26257

test plan:

on the question bank page tab to the bookmark icon
next to a QB and press enter

the kb focus should stay on the icon

Change-Id: I3ea57d8e25076fd62989c180e64fe02660618a2a
Reviewed-on: https://gerrit.instructure.com/70433
Tested-by: Jenkins
Reviewed-by: Matt Berns <mberns@instructure.com>
QA-Review: Michael Hargiss <mhargiss@instructure.com>
Product-Review: Nathan Rogowski <nathan@instructure.com>

public/javascripts/question_banks.js

@@ -53,6 +53,7 @@ $(document).ready(function() {
     var $bank = $link.parents(".question_bank");
     $.ajaxJSON($(this).attr('href'), 'POST', {}, function(data) {
       $bank.find(".bookmark_bank_link").toggle();
+      $bank.find(".bookmark_bank_link:visible:first").focus();
     });
   });
   $(".question_bank .edit_bank_link").click(function(event) {