Add run_once task key

This caused the task to act like  bypass host loop plugin and
execute only on a single host. Can be used with delegate_to
Allow public_key to be a path to a file
Add PTR record support to rax_dns_record
Add user_data and config_drive support
Switch functions over to kwargs to make it easier to manage in the future
Mention that user_data can be a file path or a string
Allow search_regex to be used in wait_for with port
Add rackconnect and managed cloud automation check examples
Allow --vault-password-file to work with a script as well as a flat file
Show delegate_to hint in callbacks
Fix #8047

Ensure that json is returned when only updating the cache and in check mode
Make 'compress' optional
Ensure version is a string
Correct typo
Fix indentation in ec2.py
Fix logic bug when loading vars for a new playbook basedir.
Invalidate host/group variables cache when loading

extra varsiables based on playbook basedir.
Merge branch 'sergevanginderachter-vars4pb_basedir' into devel
Merge pull request #7477 from sivel/rax-user-data

rax module: Support config_drive and user_data
Merge pull request #7478 from sivel/rax-keypair-filepath

rax_keypair module: Allow public_key to be a path to a file