Somatic mutation reference implementation from dnaalnqc workflow

[justinjj24]

Can ARGO / @lindaxiang detail the dnaalnqc somatic variants pipeline?

• Input reference data / benchmark
• list of Key Metrics
• list of tools used
• Any novel metrics applied
• Metric definition 

[justinjj24]

ARGO, created new feature branch feature/somatic-variant-metrics for metric definitions of somatic mutation QC standrads..
https://github.com/ga4gh/quality-control-wgs/blob/origin/feature/somatic-variant-metrics/metrics_definitions/metrics_definitions.md