Store specimen level non-variant measures

For TSO they measure a number of things, eg HRD, and:

```
Tumour Mutation Burden 3.1 (Low)
Microsatellite Status 5.1% (Stable)
```

It would be good to be able to store this

I think technically it should be against a specimen, as Sample represents VCF / sequencing sample, specimen is the solid tumor from a particular tissue/timepoint for a patient.