We couldn't copy to_unicode, to_bytes, to_str into module_utils because
of licensing. So once created it we had two sets of functions that did
the same things but had different implementations. To remedy that, this
change removes the ansible.utils.unicode versions of those functions.
On Python 2, shlex.split() raises if you pass it a unicode object with
non-ASCII characters in it. The Ansible codebase copes by explicitly
converting the string using to_bytes() before passing it to
shlex.split().
On Python 3, shlex.split() raises ('bytes' object has no attribute 'read')
if you pass a bytes object. Oops.
This commit introduces a new wrapper function, shlex_split, that
transparently performs the to_bytes/to_unicode conversions only on
Python 2.
Currently I've only converted one call site (the one that was causing a
unit test to fail on Python 3). If this approach is deemed suitable,
I'll convert them all.