Ensure that KStandardDirs always returns resolved paths (when $HOME or $KDEHOME is a symlink),
even when returning paths that don't exist yet. Otherwise, via caches (the kstandarddirs one
or in applications), we can end up with a different path once it does exist, and comparisons
will fail (e.g. the one in KConfigPrivate::parseConfigFiles which detects the local file).

(So this fixes "kconfigtest testRevertAllEntries" when $HOME is a symlink, but has its own
setup-independent unittest now)