Add support multicore CPU in Batch Queue Manager to process items from queues in parallel.

This will speed up items processing depending of cores available in your computer.
Detection of core suitable is done through KDE::Solid API.
Registration of items properties is not paralellized yet and still in main thread.
It can be a bottleneck in the workflow. This point must be analyzed later with core Database interface.
BUGS: 254033
FIXED-IN: 3.0.0