Improve uncerParsing in parseExpandedUnc from parseUncertainties.py

Tasks

[] Cast all uncertainties to std with k=1 [] Store old uncertainty information and distribution in ValueQunatities [] Handle old uncer formats in xml/json creation

use def test_basic(): from https://gitlab1.ptb.de/digitaldynamicmeasurement/dccQuantities/-/blob/devel-serializer/tests/test_serilizer.py