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
Fixed tracebacks when datacenter not found, when notes not given, and when collecting facts after VM creation. Fixes #8067.
Re-fixing ability to have empty json files after inventory refactoring
Errors out with stderr 1049, unknown database: when importing a database that does not exist
Correct regex in is_keyid

The `rpm_key` module claims to take a key ID as an argument, however it fails if one is actually given:

    msg: Not a valid key DEADBEEF

The reason for this is the regular expression in the `RpmKey.is_keyid` method is incorrect; it will only match the literal string "0-9a-f" exactly 8 times, rather than exactly 8 characters in the set 0-9 or a-f.
Merge pull request #8094 from ghjm/vsphere-fixes

Fixed tracebacks during VM creation. Fixes #8067.
Merge pull request #8104 from AdmiralNemo/patch-1

Correct regex in is_keyid
Merge pull request #8103 from Jmainguy/mysql_db_6214

mysql_db: Fix error message for #6214
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.