Support new somatic and oncogenic clinical classifications

[apriltuesday]

As discussed when we migrated to the new XML format in #396, the new format includes a new structure as well as new terms for clinical classification (previously called clinical significance) for somatic and oncogenic classifications in particular. At the time we decided to postpone supporting these until we had more concrete examples to use to model them. We are now starting to see increasing numbers of these ClinVar records, so we now have these examples and it seems the trend is that it will be increasingly important to support them.

Tasks:

• Review the new fields and look at examples from #446
• Discuss what schema and pipeline changes to make

[apriltuesday]

@tcezard @DSuveges @ireneisdoomed Hi all, I've looked a bit into usage of the new somatic/oncogenic classifications in the recent ClinVar dump and summarised my findings here, alongside some examples and rough schema ideas. Let me know your thoughts and questions.