[ticket/12351] Add loading indicator to links that are missing it.

When you click on the link, the turning circle is missing, so you don't
know whether it is actually doing something or not, until the response is
served.

PHPBB3-12351
Merge remote-tracking branch 'VarunAgw/ticket/12351' into develop-ascraeus

* VarunAgw/ticket/12351:
  [ticket/12351] Add loading indicator to links that are missing it.