Checks JSON

This MR adds a function to serialise all information about checks for a job in a JSON file. This is working towards making check results available in the AP web app.

The creation of this checks.json file for local tests is added in lbaplocal!31 (merged)

Still to do: JSON Serialization of hist histograms

Work related to https://gitlab.cern.ch/lhcb-dpa/project/-/issues/93