Add ansible_sudo_pass support, Fixes #4323

Uses ansible_sudo_pass hostvar, otherwise -K/--ask-sudo-pass if provided, or lastly ansible_ssh_pass

Fixes #4323
Small logic change to test if vars are None
Detect when sudo doesn't require a password
Don't fall back

Don't fall back to ansible_ssh_pass or to -K/--ask-sudo-pass

Hostvars override prompt provided vars, so do that here too
Update the success_key to include the word SUDO