[ticket/12322] CSS classes for postprofile-profile <dd> items

There is no subsilver2 equivalent for this commit

PHPBB3-12322
[ticket/12322] Added profile-custom-field class

PHPBB3-12322
Merge remote-tracking branch 'paybas/ticket/12322' into develop-ascraeus

* paybas/ticket/12322:
  [ticket/12322] Added profile-custom-field class
  [ticket/12322] CSS classes for postprofile-profile <dd> items