(I don't have a system with selinux to test if the module still wants
byte strings even on Python 3.)

This caused an ImportError in a test module and showed up as one test
failure.  Now the test module can get imported and many more tests fail
(on Python 3).  Such is life.  ;-)

 * allow global no_log setting, no need to set at play or task level, but can be overriden by them
 * allow turning off syslog only on task execution from target host (manage_syslog), overlaps with no_log functionality
 * created log function for task modules to use, now we can remove all syslog references, will use systemd journal if present
 * added debug flag to modules, so they can make it call new log function conditionally
 * added debug logging in module's run_command

Due to the way we're now calculating delegate_to, if that value is based
on a loop variable ('item') we need to calculate all of the possible
delegated_to variables for that loop.

Fixes #12499

There doesn't appear to be anything that actually uses tmp_path in the
connection plugins so we don't need to pass that in to exec_command.
That change also means that we don't need to pass tmp_path around in
many places in the action plugins any more.  there may be more cleanup
that can be done there as well (the action plugin's public run() method
takes tmp as a keyword arg but that may not be necessary).

As a sideeffect of this patch, some potential problems with chmod and
the patch, assemble, copy, and template modules has been fixed (those
modules called _remote_chmod() with the wrong order for their
parameters.  Removing the tmp parameter fixed them.)

The value was useless -- unused by the callers and always hardcoded to
the empty string.

Also, on Python 3 the stock object.__hash__ raises an error ("unhashable
type"), and we have code that uses Host instances as dict keys.

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.

There were no inventory-specific unit tests earlier, so we add a new
directory for them with some initial low-level tests of _split_pattern
with various valid and deprecated pattern strings.

Fixes #12053

Labels must start with an alphanumeric character, may contain
alphanumeric characters or hyphens, but must not end with a hyphen.
We enforce those rules, but allow underscores wherever hyphens are
accepted, and allow alphanumeric ranges anywhere.

We relax the definition of "alphanumeric" to include Unicode characters
even though such inventory hostnames cannot be used in practice unless
an ansible_ssh_host is set for each of them.

We still don't enforce length restrictions—the fact that we have to
accept ranges makes it more complex, and it doesn't seem especially
worthwhile.

This adds a parse_address(pattern) utility function that returns
(host,port), and uses it wherever where we accept IPv4 and IPv6
addresses and hostnames (or host patterns): the inventory parser
the the add_host action plugin.

It also introduces a more extensive set of unit tests that supersedes
the old add_host unit tests (which didn't actually test add_host, but
only the parsing function).

There was code to support set literals (on Python 2.7 and newer), but it
was buggy: SAFE_NODES.union() doesn't modify SAFE_NODES in place,
instead it returns a new set object that is then silently discarded.

I added a unit test and fixed the code.  I also changed the version
check to use sys.version_tuple instead of a string comparison, for
consistency with the subsequent Python 3.4 version check that I added in
the previous commit.

Fixes #12245

The full error was

======================================================================
ERROR: test_task_executor_execute (units.executor.test_task_executor.TestTaskExecutor)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/mg/src/ansible/test/units/executor/test_task_executor.py", line 252, in test_task_executor_execute
    mock_action.run.return_value = dict(ansible_facts=dict())
  File "/home/mg/src/ansible/lib/ansible/executor/task_executor.py", line 317, in _execute
    if self._task.async > 0:
TypeError: unorderable types: MagicMock() > int()

----------------------------------------------------------------------

Experiments show that Python 2 MagicMock() > 0 is true, so I'm setting
the async property on mock_task to 1.  (If I set it to 0, the test fails
anyway.)

Required some rewiring in inventory code to make sure we're using
the DataLoader class for some data file operations, which makes mocking
them much easier.

Also identified two corner cases not currently handled by the code, related
to inventory variable sources and which one "wins". Also noticed we weren't
properly merging variables from multiple group/host_var file locations
(inventory directory vs. playbook directory locations) so fixed as well.

simplify become testing and handling, we had drifted and were doulbe checking prompt, become and become_pass
fixed tests to conform to new signature and now tests both with and w/o password
now we are more explicit about self.prompt

Fixes #12198
Fixes #12241

Also fix the bug (missing from six import iteritems) I introduced in
823677b4.

Replace .iteritems() with six.iteritems() everywhere except in
module_utils (because there's no 'six' on the remote host).  And except
in lib/ansible/galaxy/data/metadata_template.j2, because I'm not sure
six is available there.