Add simple install script to avoid cmake&deps

[junghans]

Helps with #2149

[copy-pr-bot]

This pull request requires additional validation before any workflows can run on NVIDIA's runners.

Pull request vetters can view their responsibilities here.

Contributors can view more details about this message here.

[ericniebler]

iiuc, this helps with the header-only parts of stdexec, is that right? that is not all of stdexec. in particular, the implementation of stdexec::parallel_scheduler is typically separately compiled.

[junghans]

Yes, this is for header-only, but let’s close this in favor of #2341, which is the better solution!