WIP: cudaPackages.cudatoolkit: split outputs

[SomeoneSerge]

Description of changes

Split outputs of cudaPackages.cudatoolkit so that the actual toolkit does not bring in dependencies of graphical/interactive apps (e.g. the debugging tools such as nsight) into the closure.

Note this is a work in progress

[SomeoneSerge]

Here's the plan: I could create an intermediate derivation, say let cudatoolkit-src = ...; in, which would would only have the unpackPhase (same as one in current expression) and an installPhase that moves stuff to $out verbatim, without any patchelf. Then I'd rewrite cudatoolkit to take src = cudatoolkit-src, to extract the actual toolchain without nsight, and to apply autoPatchelf. Similarly, I can have a separate expression for nsight with src = cudatoolkit-src.
This way the outPath of cudatoolkit-src never really changes, and cudatoolkit does not depend on python2 or gtk3

@samuela, thoughts? An overkill? I just want a quick solution to reduce the closure sizes right away, then I'll forget this and get back to redist packages

[samuela]

I'm not against this, but I imagine that it will eventually be made obsolete by the redist packages anyhow... So I guess it all comes down to how you'd prefer to spend your refactoring time :P

[SomeoneSerge]

I'm not against this, but I imagine that it will eventually be made obsolete by the redist packages anyhow... So I guess it all comes down to how you'd prefer to spend your refactoring time :P

I just thought I'd pull this one off in no time, but in the end I can only afford occasional small contributions =
I'm closing this and will prioritize migrating pytorch/tf/jaxlib to redist instead