Handle multi-allelic vcf with alternative alleles separated per row (i.e. generated via bcftools norm -m -

[jeffersonfparil]

Since we have to convert all other formats into sync which we can properly handle multi-allelic loci, then let's just handle multi-allelic vcfs and properly convert them into syncs. This is instead of our current error message telling users to remove multi-row multi-allelic loci.