Implements https://phabricator.kde.org/T10971
This adds the KDE Applications version to all projects. That makes sense since it's the version number used in the tars and so the version number user in the packaging.
But if it's not wanted on apps which prefer to use their own internal version number I'm not sure how to distinguish them. Check for cmake having a line like this?
project(bomber VERSION ${KDE_APPLICATIONS_VERSION})