Enable brower-default outlines on links

This code was from Spree. Unless you have good focus/active styles for all links, the outline is very helpful for accessibility.
Most websites these days add nice thick outlines, which might be worth considering in the future.

app/webpacker/css/admin_v3/shared/typography.scss

@@ -51,14 +51,6 @@ a:not(.button) {
   text-decoration: none;
   line-height: inherit;
 
-  &,
-  &:hover,
-  &:active,
-  &:visited,
-  &:focus {
-    outline: none;
-  }
-
   &:visited {
     color: $color-link-visited;
   }