Add support for protein variation in translate_to()

[jarbesfeld]

translate_to() currently supports translation to HGVS strings for nucleic acid variation but not protein variation

[korikuzma]

For now, we won't worry about trying to normalize protein variants since biocommons.hgvs does not support protein normalization yet. Will make an issue soon to address.

[korikuzma]

This issue will also be helpful for our VarCat project. Given gnomad vcf representation, we use the VICC Variation Normalizer to translate to the VRS Object on the protein sequence. We need to be able to get the protein hgvs expression from this.

[github-actions]

This issue was marked stale due to inactivity.