Add ansible_sudo_pass hostvar support. Fixes #4323

A few notes about this change.

I updated `make_sudo_cmd` to echo a "success" key as part of the sudo command.  This allows for the scenario where sudo may not require a password but one was given.

Additionally `make_sudo_cmd` now returns a 3 element tuple, now including the `success_key`.

Where applicable (local, paramiko, ssh), the sudo code, has been updated to make use of the new `success_key`.