Adjust to new somatic/germline structure

[holtgrewe]

Describe the bug
ClinVar has updated their data structures with a separation of somatic and germline variants. Without adding support for this, we cannot parse current ClinVar XML.

To Reproduce
N/A

Expected behavior
We need to add parsing support for both germline and somatic variants. We will need to write out both th <e old assessment information and add support for the new one.

Additional context

• https://ncbiinsights.ncbi.nlm.nih.gov/2024/02/29/submit-somatic-data-to-clinvar/
• https://ncbiinsights.ncbi.nlm.nih.gov/2023/02/01/clinvar-support-for-somatic-data/
• https://github.com/ncbi/clinvar ⭐

[holtgrewe]

It is probably most promising to first generate a protobuf file from the ClinVar XSD. The one existing converter appears to be schema2proto. However, it has problems:

• NPE when converting ClinVar XSD file entur/schema2proto#570