Add Support for Health Checks

[SMAPPER]

It would be great if the elastic-ilm support custom health checks with remediation based on client_info.json.

Example client info:

Example client info entry

# "custom_checks": {
#     "0": {
#     "check": "/bin/bash /opt/elastic_stack/scripts/verify_acuity_custom_service.sh",
#     "remediate": "/bin/bash /opt/elastic_stack/scripts/restart_acuity_custom_service.sh",
#     "schedule": "15",
#     "remediation_retries": "3",
#     }
# },

Schedule would be dynamically set per entry. Thoughts?

• Add support for health checks. Look for proper exit code
• Add support for remediation checks. Run if check fails to exit properly
• Add support for custom schedules per health check
• Add support for remediation retry so it doesn't keep trying to remediate indefinitely