It is supposed to broadcast application job progress to multiple interested parties.
However, effectively it was just plasmashell. Cut the middleman, including its never finished and unused UI,
and talk to plasmashell directly.
The applicationjobs dataengine is adjusted to use the new infrastructure instead.
Since it works only in the same process now, Unity launcher API is used to at least broadcast basic
application progress information for use in e.g. Latte Dock.
Also, introduce JobViewServerV2 and JobViewV3 APIs which are using desktop entries for identification rather
than application names, and more importantly are extensible using a QVariantMap hints, so adding new
fields in the future should be significantly less painful with Frameworks, Applications, and Plasma all having
their own release schedule. :)
Use own copy of org.kde.JobView interface file to make it possible to
extend the interface without breaking build.
This also fixes 2 cases where error/errorText would be incorrect in
applicationsjob dataengine.
REVIEW: 123046