EVA-3914: Update ClinVar diagrams

[apriltuesday]

• Updated to work with XML V2 and generate sankey diagrams directly from the script.
• I tried to make the diagrams presentable but didn't invest too much time perfecting them, since they will likely change in the future.
• I did not update the report text that surrounds the diagrams in the readme - I'm not sure whether we should actually update this report directly, or whether we should keep it (with its current diagrams) and start on a new report if we change the diagrams altogether.

Closes #433