bug#71031: [PATCH] Added r-mcview

[Ricardo Wurmus]

Thank you for this excellent first contribution!

This one is a little tricky: mcview depends on r-waiter and
r-shinywidgets, both of which bundle a lot of minified JavaScript from
unknown sources.

Today I finished packaging r-waiter by replacing its use of webpack with
esbuild (for which we do have a usable package).  This required
modification of the esbuild package, which I did in a variant
"esbuild-node" to build and install the nodejs libraries.

Alas, I wasn't able to do the same for r-shinywidgets.  This package
still lives in Guix Science for this reason.

I split your patch into several commits, one for each package.  Those
packages that depend on things that are in Guix Science have been moved
there.  This includes r-mcview itself.  Everything else is now in Guix
proper.

I've moved packages from bioinformatics.scm to cran.scm where
appropriate (arranged roughly in alphabetic order).

Thanks again for this contribution and welcome to Guix!

-- 
Ricardo