Returns alternative expressions of `hgvs`, including the given expression.

There can be multiple HGVS expressions for the same variant. For example,
"NM_123.4:c.4_6[1]" and "NM_123.4:c.7_9del" can be equivalent in some
cases. When you give either of the two HGVS, `find-aliases` returns both HGVS.

`hgvs` must be a coding DNA HGVS with a transcript. `ref-seq` must be a path
to reference or an instance which implements
`cljam.io.protocols/ISequenceReader`. `ref-gene` must be a path to
refGene.txt(.gz), a ref-gene index, or a ref-gene entity.