Add rake task for health check

What does this MR do and why?

Usage

bundle exec rake cloud_connector:health_check\[true,root,report.json\]

Report

[
  {
    "name": "license_probe",
    "success": true,
    "message": "Subscription can be synchronized.",
    "details": [

    ],
    "errors": [

    ]
  },
  {
    "name": "host_probe",
    "success": true,
    "message": "localhost reachable.",
    "details": [

    ],
    "errors": [

    ]
  },
  {
    "name": "host_probe",
    "success": true,
    "message": "cloud.gitlab.com reachable.",
    "details": [

    ],
    "errors": [

    ]
  },
  {
    "name": "access_probe",
    "success": true,
    "message": "Subscription synchronized successfully.",
    "details": [

    ],
    "errors": [

    ]
  },
  {
    "name": "end_to_end_probe",
    "success": false,
    "message": "Authentication with GitLab Cloud services failed: Failed to open TCP connection to ::1:5052 (Connection refused - connect(2) for \"::1\" port 5052)",
    "details": [

    ],
    "errors": [

    ]
  }
]

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