noarch / script shebang issues / warn about entrypoints

[wolfv]

We got a report that rattler-build creates entry points for noarch-python with unquoted paths.

For example:

#!/bin/sh
'''exec' /foo/bar ...

where /foo/bar is not quoted, and replaced at install time with another unquoted string.

I believe pip created these unquoted paths and not rattler-build.

But we should also warn about creating scripts that are not necessary (since entry_points are preferred!).