##### SUMMARY
Support become unprivileged user on macOS without `allow_world_readable_tmpfiles=true`

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
action, shell, and copy

##### ADDITIONAL INFORMATION
When using become where the login user and the become user are both unprivileged, Ansible attempts to securely change file permissions to only allow the become user to read the files. It uses `setfacl` and falls back to `chown`. Both of these fail on macOS, as there is no `setfacl` command and `chown` is not permitted.

macOS actually does provide the same functionality as `setfacl`, using `chmod +a`. The syntax is a bit different from `setfacl`, but it should be able to do what Ansible needs.
""" Action Plugins should implement this method to perform their
        tasks.  Everything else in this base class is a helper method for the
        action plugin to do that.
        :kwarg tmp: Deprecated parameter.  This is no longer used.  An action plugin that calls
            another one and wants to use the same remote tmp for both should set
            self._connection._shell.tmpdir rather than this parameter.
        :kwarg task_vars: The variables (host vars, group vars, config vars,
            etc) associated with this task.
        :returns: dictionary of results from the module
        Implementors of action modules may find the following variables especially useful:
        * Module parameters.  These are stored in self._task.args
        """
        result = {}