Move uses of to_bytes, to_text, to_native to use the module_utils version (#17423)

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.

lib/ansible/plugins/callback/mail.py

@@ -25,9 +25,10 @@ import smtplib
 import json
 
 from ansible.compat.six import string_types
-from ansible.utils.unicode import to_bytes
+from ansible.module_utils._text import to_bytes
 from ansible.plugins.callback import CallbackBase
 
+
 def mail(subject='Ansible error mail', sender=None, to=None, cc=None, bcc=None, body=None, smtphost=None):
 
     if sender is None:
@@ -84,7 +85,7 @@ class CallbackModule(CallbackBase):
         if ignore_errors:
             return
         sender = '"Ansible: %s" <root>' % host
-        attach =  res._task.action
+        attach = res._task.action
         if 'invocation' in res._result:
             attach = "%s:  %s" % (res._result['invocation']['module_name'], json.dumps(res._result['invocation']['module_args']))