add session and power mgmt runners to kickoff
Summary:
It's a bit weird that kickoff's leave tab has power management actions but
you cannot actually invoke them via a search.
CHANGELOG: Application Launcher supports searching for power actions
Test Plan: changed, searching for shutdown lists the actual shutdown runnable as result
Reviewers: hein, broulik
Reviewed By: hein
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D6020