refactor: multi-level snapshot comparison and config parser refactor

[alperenkose]

Description

This is a draft PR for review. Unit tests and docstrings need to be updated with code clean-up.

This PR enhances snapshot comparison by allowing properties to be filtered on different levels of the snapshots.
missing/added comparison fields are also filtered according to the properties set.
It includes refactoring of ConfigParser class providing usable static methods for SnapshotComparison.

Motivation and Context

It fixes the issue #108 and complements the draft #109 PR.

In addition to the mentioned issue, considering the below snapshots (snapshot-1 and snapshot-2), it makes it possible to compare/exclude fields on different levels. See all possible examples below:

        {"license": {
            "properties": ["PAN-DB URL Filtering"]  # comparison for parent level
        }},
        {"license": {
            "properties": ["!Logging Service"]  # also support if property exists in different levels in different dicts
        }},
        {"license": {
            "properties": ["issued", "PAN-DB URL Filtering"]  # multi-level "AND" operation (combination with parent) for properties is not supported on purpose - "PAN-DB URL Filtering" diff will be made for all its attributes since its the parent
        }},

        # 1st and 2nd level keys
        {"license": {
            "properties": ["!_Log_Storage_TB"]
        }},
        {"license": {
            "properties": ["_Log_Storage_TB"]
        }},
        {"license": {
            "properties": ["_Log_Storage_TB","issued"]
        }},
        {"license": {
            "properties": ["issued", "!logtype"]
        }},
        {"license": {
            "properties": ["serial", "!logtype"]
        }},
        {"license": {
            "properties": ["custom"]
        }},
        {"license": {
            "properties": ["!custom"]
        }},
        {"license": {
            "properties": ["alogging"]
        }},
        {"license": {
            "properties": ["blogging"]
        }},
        {"license": {
            "properties": ["something"]  # since no such key is there it passes - works
        }},
        {"license": {
            "properties": ["serial", "non-existing"] # compare only requested
        }},
        {"license": {
            "properties": ["all"]
        }},
        {"license": {
            "properties": ["!issued", "all"] # compare all except
        }},
        {"license": {
            "properties": ["!logtype"]
        }},
        {"license": {
            "properties": ["!Logging Service", "issued"]
        }},

snapshot-1

{
  "license": {
    "Logging Service": {
      "authcode": null,
      "custom": {
          "_Log_Storage_TB": "7",
          "logtype": "disk",
          "alogging": "enabled"
      },
      "description": "Device Logging Service",
      "expired": "no",
      "expires": "August 04, 2024",
      "feature": "Logging Service",
      "issued": "June 27, 2022",
      "serial": "013201027229"
    },
    "Y feature": {
      "authcode": null,
      "description": "Device Logging Service",
      "expired": "no",
      "expires": "August 04, 2024",
      "feature": "Logging Service",
      "issued": "June 29, 2022",
      "serial": "013201027248"
    },
    "PAN-DB URL Filtering": {
      "Logging Service": "somehting",
      "authcode": null,
      "description": "Palo Alto Networks URL Filtering License",
      "expired": "no",
      "expires": "June 30, 2028",
      "feature": "PAN-DB URL Filtering",
      "issued": "April 27, 2023",
      "serial": "013201027229"
    },
    "C feature": {
      "authcode": null,
      "description": "Palo Alto Networks URL Filtering License",
      "expired": "no",
      "expires": "June 30, 2028",
      "feature": "PAN-DB URL Filtering",
      "issued": "April 27, 2023",
      "serial": "013201027229"
    }
  }
}

snapshot-2

{
  "license": {
    "Logging Service": {
      "authcode": null,
      "custom": {
          "_Log_Storage_TB": "9",
          "logtype": "tape",
          "blogging": "enabled"
      },
      "description": "Device Logging Service",
      "expired": "no",
      "expires": "August 04, 2024",
      "feature": "Logging Service",
      "issued": "June 29, 2022",
      "serial": "013201027229"
    },
    "X feature": {
      "authcode": null,
      "description": "Device Logging Service",
      "expired": "no",
      "expires": "August 04, 2024",
      "feature": "Logging Service",
      "issued": "June 29, 2022",
      "serial": "013201027248"
    },
    "PAN-DB URL Filtering": {
      "authcode": null,
      "description": "Palo Alto Networks URL Filtering License",
      "expired": "no",
      "expires": "June 30, 2028",
      "feature": "PAN-DB URL Filtering",
      "issued": "April 29, 2023",
      "serial": "013201027248"
    },
    "C feature": {
      "authcode": null,
      "description": "Palo Alto Networks URL Filtering License",
      "expired": "no",
      "expires": "June 30, 2028",
      "feature": "PAN-DB URL Filtering",
      "issued": "April 27, 2023",
      "serial": "013201027229"
    }
  }
}

How Has This Been Tested?

Tested with example scripts.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes if appropriate.
• All new and existing tests passed.

[alperenkose]

Test with:

- nics:

This is a valid yaml with empty dict.