rebuild with a local source path doesn't work

[rgommers]

When using a local source path with a relative path, rattler-build rebuild (perhaps not completely surprisingly) fails to locate the source because rebuild extracts the recipe from the conda package into a tmpdir, and the relative path no longer works. This bug report is twofold:

1. If this is a current limitation of rebuild, it would be good to note that in the docs.
2. The error message is too hard to understand and should be improved.

I tried with this recipe for scipy. It contains:

source:
  path: ../scipy
  use_gitignore: false

After building the package and attempting to use rebuild, this is the error message:

$ rattler-build rebuild -p output/linux-64/scipy-1.15.0.dev0-py312h738df08_0.conda 
 Rebuilding output/linux-64/scipy-1.15.0.dev0-py312h738df08_0.conda
 Extracted recipe to: "/tmp/.tmp72w1NQ"
Error:   × IO Error: No such file or directory (os error 2)
  ╰─▶ No such file or directory (os error 2)

That same obscure error message occurs if you put a type into the local path and run rattler-build build, something like this in any recipe:

source:
  path: non-existing

It would be really helpful if the error message identified what file or directory cannot be located.