* Add ACME health checks to pki health-check CLI
- Verify we have the required header values listed within allowed_response_headers: 'Replay-Nonce', 'Link', 'Location'
- Make sure the local cluster config path variable contains an URL with an https scheme
* Split ACME health checks into two separate verifications
- Promote ACME usage through the enable_acme_issuance check, if ACME is disabled currently
- If ACME is enabled verify that we have a valid
'path' field within local cluster configuration as well as the proper response headers allowed.
- Factor out response header verifications into a separate check mainly to work around possible permission issues.
* Only recommend enabling ACME on mounts with intermediate issuers
* Attempt to connect to the ACME directory based on the cluster path variable
- Final health check is to attempt to connect to the ACME directory based on the cluster local 'path' value. Only if we successfully connect do we say ACME is healthy.
* Fix broken unit test