Add "expected same number of samples for all inputs" exception thrown by Hail to validation exceptions.

e.g.:

```
Error summary: HailException: invalid sample IDs: expected same number of samples for all inputs.
 gs://fc-687ad018-6f7d-452e-a14f-b385c90def20/Shen_HearNSeq.VQSR.subset2.vcf.gz has 75 ids and
 gs://fc-687ad018-6f7d-452e-a14f-b385c90def20/Shen_HearNSeq.VQSR.subset4.vcf.gz has 72 ids.
```