Have all krunner plugin desktop files prefixed with "plasma-runner-"
Summary:
With all desktop files being installed in KDE_INSTALL_KSERVICES5DIR,
having a namespace prevents clashes and also helps identifying the files.
Reviewers: Plasma, broulik, apol
Reviewed By: apol
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D10515