This package should never be added to systemPackages or other global
environments as it will not provide any function there. Making its $out a file
will prevent buildEnv from including it; providing an error like this:
error: The store path /nix/store/wxl3m27dmjjsfqvzzxw7ibr0gr54wwkp-proton-ge-bin-GE-Proton9-1 is a file and can't be merged into an environment using pkgs.buildEnv! at /nix/store/ndhb3bsaf3zc6gx22vjl0w11sxvapf7b-builder.pl line 122.
Some breadcrumbs are left inside the file.
This sets a standard for Steam compat tools in NixOS where they must have the
compat tool in a special steamcompattool output.
proton-ge-bin was adjusted to conform with it.