Which does the rendering and proper sizing for us, e.g. ensure integer scaling so the barcode remains scannable.
While at it, fix supportsBarcode (wasn't routed through to the delegate component when it was split out)
and add Code 128 which is in Prison now.
Also, show a label when the barcode would become too large to display (mostly for the 1D barcodes).
The Prison item does not use a thread for generating the barcode like the dataengine does but it's super fast.

Differential Revision: https://phabricator.kde.org/D29478