Lyndon Brown authored Apr 12, 2019 and Jean-Baptiste Kempf committed Jun 11, 2021

i have a use for `CONFIG_CLASS` now in the qt prefs code, and elsewhere in
later work.

the other test macros may be useful to have publicly for preference
interface code so were moved also, and besides, having them all in one
place makes finding them and maintaining them easier. there's no harm in
exposing them to plugins.