Standardize h5ad/seurat var gene annotations across aligners

[alexblaessle]

Description of feature

Dear all

I just found out that in commit aae5fc5 we moved away from having ensembl_gene_ids as standard feature identifier for kallisto.

Even though gene names are generally desired by users, they are not necessarily persistent identifiers. I would suggest that each aligner outputs an h5ad/seurat with ensembl_gene_id as var index and an additional column "gene_symbol" or "gene_name".

Tagging @grst @fmalmeida @apeltzer

[grst]

I'm all for it and this ties in with #310.
I don't have capacity to tackle this myself right now, but if you task @fmalmeida or other ZS folks I'm happy to provide input.