Kill Runner: Move config keys to new file
Summary:
The config keys/sorting enum have been moved to a new file, before this the runner included the header of the config class.
This patch originated from https://phabricator.kde.org/D27513, but it was requested to split it up into separate patches.
Test Plan: Should compile.
Reviewers: davidedmundson, ngraham, broulik, meven, apol
Reviewed By: meven
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D27576