Treat paths in submodule relative to directory of root `.justfile`

[Splines]

It'd be great to have an option to treat all paths in a submodule relative to the directory containing the root .justfile. I think I'd prefer a per-module flag for this instead of a global one.

This would allow me to let my submodules reside in other file locations (e.g. in a folder .config/commands/), while not having to issue a cd {{justfile_directory()}} or cd ../../ at the beginning of every recipe.