Open source the Data Challenge scoring code

Making the scoring code available in python will allow data challenge teams to assess their own results, and test that their results catalogues are in the correct format (saving Anna's time). We can then look towards containerising the assessment code as an example to show the data challenge teams how they can create containers. This is part of a longer-term effort to get the various data challenge teams to containerise their algorithms so we can make comparisons of run-time performance on different hardware. This is a step towards making future science data challenges more autonomous so that effort within SKAO can go into the development of the challenges themselves and not be taken up so much in help-desk type support of queries about the procedures, formats etc.