Update nixglhost.py to pass all remainder ARGS to NIX_BINARY

addresses https://github.com/numtide/nix-gl-host/issues/26 - this is technically breaking behavior wrt current shell semantics (because you can run `nixglhost my-binary -- -arg1 -argn` right now; but this PR makes the `--` token also an arg) - no other testing beyond verification in the shell that e.g. `nixglhost date -u` works as expected