validate-modules: don't error on valid Ansible YAML in EXAMPLES

[flowerysong]

SUMMARY

Use Ansible's custom loader to support tags like !unsafe during YAML validation.

When a module takes a parameter that usually needs to be marked unsafe, it should be able to provide usable examples in the documentation without failing sanity tests.

ISSUE TYPE

• Bugfix Pull Request

COMPONENT NAME

validate-modules

ADDITIONAL INFORMATION

EXAMPLES = '''
- name: Configure LDAP authentication
  flowerysong.hvault.ldap_config:
    url: ldaps://ldap.umich.edu
    userdn: ou=People,dc=umich,dc=edu
    userattr: cn
    groupdn: ou=User Groups,ou=Groups,dc=umich,dc=edu
    groupfilter: !unsafe (member={{.UserDN}})
    groupattr: cn
'''

Without this change:

Running sanity test 'validate-modules' with Python 3.7
ERROR: Found 1 validate-modules issue(s) which need to be resolved:
ERROR: plugins/modules/ldap_config.py:152:18: invalid-examples: EXAMPLES is not valid YAML