Various python3 updates for module_utils: (#17345)

* Port set_*_if_different functions to python3
* Add surrogate_or_strict and surrogate_or_replace error handlers for
  to_text, to_bytes, to_native
* Set default error handler to surrogate_or_replace
* Make use of the new error handlers in the already ported code
* Move the unittests for module_utils._text as they aren't in basic.py
* Cleanup around SEQUENCETYPE.  On python2.6+ SEQUENCETYPE includes
  strings so make sure code omits those explicitly if necessary
* Allow arg_spec aliases to be other sequence types

lib/ansible/module_utils/_text.py

@@ -35,6 +35,13 @@
 
 from ansible.module_utils.six import PY3, text_type, binary_type
 
+import codecs
+try:
+    codecs.lookup_error('surrogateescape')
+    HAS_SURROGATEESCAPE = True
+except LookupError:
+    HAS_SURROGATEESCAPE = False
+
 def to_bytes(obj, encoding='utf-8', errors=None, nonstring='simplerepr'):
     """Make sure that a string is a byte string
 
@@ -47,8 +54,22 @@ def to_bytes(obj, encoding='utf-8', errors=None, nonstring='simplerepr'):
     :kwarg errors: The error handler to use if the text string is not
         encodable using the specified encoding.  Any valid `codecs error
         handler <https://docs.python.org/2/library/codecs.html#codec-base-classes>`_
-        may be specified. On Python3 this defaults to 'surrogateescape'.  On
-        Python2, this defaults to 'replace'.
+        may be specified. There are two additional error strategies
+        specifically aimed at helping people to port code:
+
+            :surrogate_or_strict: Will use surrogateescape if it is a valid
+                handler, otherwise it will use strict
+            :surrogate_or_replace: Will use surrogateescape if it is a valid
+                handler, otherwise it will use replace.
+
+        Because surrogateescape was added in Python3 this usually means that
+        Python3 will use surrogateescape and Python2 will use the fallback
+        error handler. Note that the code checks for surrogateescape when the
+        module is imported.  If you have a backport of surrogateescape for
+        python2, be sure to register the error handler prior to importing this
+        module.
+
+        The default is `surrogate_or_replace`
     :kwarg nonstring: The strategy to use if a nonstring is specified in
         ``obj``.  Default is 'simplerepr'.  Valid values are:
 
@@ -71,11 +92,16 @@ def to_bytes(obj, encoding='utf-8', errors=None, nonstring='simplerepr'):
     if isinstance(obj, binary_type):
         return obj
 
-    if errors is None:
-        if PY3:
+    if errors in (None, 'surrogate_or_replace'):
+        if HAS_SURROGATEESCAPE:
             errors = 'surrogateescape'
         else:
             errors = 'replace'
+    elif errors == 'surrogate_or_strict':
+        if HAS_SURROGATEESCAPE:
+            errors = 'surrogateescape'
+        else:
+            errors = 'strict'
 
     if isinstance(obj, text_type):
         return obj.encode(encoding, errors)
@@ -126,6 +152,17 @@ def to_text(obj, encoding='utf-8', errors=None, nonstring='simplerepr'):
     if isinstance(obj, text_type):
         return obj
 
+    if errors in (None, 'surrogate_or_replace'):
+        if HAS_SURROGATEESCAPE:
+            errors = 'surrogateescape'
+        else:
+            errors = 'replace'
+    elif errors == 'surrogate_or_strict':
+        if HAS_SURROGATEESCAPE:
+            errors = 'surrogateescape'
+        else:
+            errors = 'strict'
+
     if errors is None:
         if PY3:
             errors = 'surrogateescape'