Add chr_pos_ref_alt variant IDs to non-star allele evidence strings

[apriltuesday]

Currently we provide rsIDs where present and genotypeIDs of the form chr_pos_ref_allele1,allele2. It's straightforward to derive variant IDs from this, but we should discuss how to report these given that the cardinality of variants per genotypeID can be 0, 1, or 2, depending on whether the genotype contains only reference alleles and whether the variant is multi-allelic.