the 'missing path' test still works, but rather
accidentally: the plugin search path retrieved from
resolving $ORIGIN is an absolute path, while this
test uses relative paths; thus the querried plugin
won't be found. In the second test, we set an
environment override, using the relative path
(which is now 'modules'). Thus the discovery works.
connect config-facade with the new BasicSetup implementation
to fetch values from setup.ini, instead of the (not implemented)
Config-system. Hook this new lookup mechanism into the
plugin loader to retrieve the search path from there
