Refactor Base Probe and introduce healh_check rake task

What does this MR do and why?

In this MR, we are introducing the cloud_connector:health_check Rake task that will reuse existing StatusCheck probes. We are going to extend existing probes, so they could collect additional information details that could be useful for debugging. Also, this MR adds support for the probes to return multiple errors, and to use ActiveModel::Validations and callbacks

The Rake task executes all health check probes.

Usage

bundle exec rake 'cloud_connector:health_check[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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