move to Bio::DB::HTS module from faidx_xs
Created by: rishidev
Changes have been made to the VEP to use Faidx (FASTA indexing from HTSlib) from Bio::DB::HTS rather than its own module. These changes are to accompany this.
Relevant pull requests are: https://github.com/Ensembl/ensembl-variation/pull/25 https://github.com/Ensembl/ensembl-tools/pull/12