Add a new standalone executable to replace X-KDE-Autostart-Condition
Summary: For systemd autostart generator will add a ExecCondition=kde-systemd-start-condition rcfile:section:entry:default As described in T12627. Needs D28421
Test Plan: Run kde-systemd-start-condition; should return 0 with a missing or incomplete argument, 255 with a false or non-existent and non-default con fig value.
Reviewers: davidedmundson, broulik, dfaure, ngraham, meven
Subscribers: plasma-devel
Tags: #plasma
Differential Revision: https://phabricator.kde.org/D28424