This removes the need of the bin/idris2_app folder and replaces
it with proper links to the nix-storage folders.
This allows the user to override IDRIS2_PREFIX which will allow
them to use --install to install libraries.
* Fix: idris2_app/ was exposed in bin/
* Remove native Idris2 wrapper that set LD_LIBRARY_PATH
* Improve new Idris2 wrapper to set Idris2 paths to out folders
The idris2 Makefile tries to use different versions of sed depending on
the OS, but nix always uses the same version. Because the version of
sed that is expected on macOS doesn't exist in the nix environment, the
build fails. Setting the OS to empty string resolves the issue.
