Add Bioc packages

[Enchufa2]

• Set up Bioc repos, so that utils::available.packages returns both CRAN and Bioc packages.
• Don't assume everything is CRAN (required at least for the naming and the sources).
• See also cran4linux/sysreqs/issues/1

[jmgs7]

Hi @Enchufa2, thank you for your excellent work again.

I would like to check about progress in bioconductor packages support, but please, don't take it as any kind off pressure, cran2copr is already a life-saver software!

Thank you very much for your attention, best regards.

JM.

[Enchufa2]

To be honest, 0% progress so far. :( This requires some serious rework of the tooling, and I didn't find the necessary time yet.