`pl.rank_genes_groups_violin` should be able to pass `**kwds` to `pl.violin`

[jpintar]

What kind of feature would you like to request?

Additional function parameters

Please describe your wishes

All the plotting functions in the pl.rank_genes_groups_<plot-type> group are able to pass additional keywords to their parent plot type for extra tuning, apart from pl.rank_genes_groups_violin. Was this by design, or is it an omission? If the latter, I'm happy to work on a PR to fix it (I found myself today wanting to pass log=True, only to get an error).