[A11Y] Adds missing focus rings back to control elements (#3016)

* Remove the stuff that removes critical accessibility features

* Remove no outline from basic blade layout

* Remove focus outline from FormControls

less/common/Dropdown.less

@@ -63,9 +63,6 @@
       &:hover {
         background: @control-bg;
       }
-      &:focus {
-        outline: none;
-      }
     }
     &.active {
       > a, > button {