layout[playbook]: New rule for detection of playbooks outside of a playbooks directory

[cidrblock]

We should be able to determine with some degree of confidence that a yaml file is a playbook and warn they should be in a ./playbooks directory.

[gone-for-coding]

I just found this feature request while looking at an issue I have with the auto detection mode (see here #2166). Isn't there already a playbook detection there:

ansible-lint/src/ansiblelint/utils.py

Line 776 in 9cc2a95

def is_playbook(filename: str) -> bool:

[cidrblock]

https://gist.github.com/cidrblock/87a874b2ac34d894dc56e8451d577eaa

This is related, although I don't think lint can fix it... :)