make services GHNS work with store.kde.org

Summary:
point the knsrc providers file to the new kde store,
and port the servicemenuinstallation/servicemenudeinstallation
scripts to kf5 (they still were based on kde4-config)
BUG:376922

Test Plan:
downloaded some service menus (send to telegram, convert svg)
by the knewstuff ui available in the services page of config dialog
they get installed in the proper folder and work, uninstall works

Reviewers: #dolphin, emmanuelp

Reviewed By: #dolphin, emmanuelp

Subscribers: elvisangelaccio

Differential Revision: https://phabricator.kde.org/D5035