Also enable shell runner for kicker

Summary: Kickoff has the shell runner enabled as part of "extraRunners" as well.

Test Plan: Typed in ls, can run ls now.

Reviewers: #plasma, hein

Reviewed By: #plasma, hein

Subscribers: ngraham, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D9093