Modify output structure

[sarangan12]

@billytrend @sergey-shandar Please review this PR. This PR is to change the output structure of the Diff Tool.

JSON Format
Old Output

{
  "id": "1001",
  "code": "NoVersionChange",
  "message": "The versions have not changed.",
  "jsonref": "#",
  "json-path": "#",
  "type": "Info"
}
{
  "id": "1006",
  "code": "RemovedDefinition",
  "message": "The new version is missing a definition that was found in the old version. Was 'DatabaseList' removed or renamed?",
  "jsonref": "#/definitions",
  "json-path": "#/definitions",
  "type": "Error"
}

Modified Output

{
  "additions": {
    "errors": [],
    "warnings": [],
    "info": []
  },
  "updates": {
    "errors": [],
    "warnings": [],
    "info": [
      {
        "message": "The versions have not changed.",
        "jsonref": "#",
        "json-path": "#",
        "id": "1001",
        "code": "NoVersionChange",
        "docurl": "https://github.com/Azure/openapi-diff/tree/master/docs/rules/1001.md"
      }
    ]
  },
  "removals": {
    "errors": [
      {
        "message": "The new version is missing a definition that was found in the old version. Was 'DatabaseList' removed or renamed?",
        "jsonref": "#/definitions",
        "json-path": "#/definitions",
        "id": "1006",
        "code": "RemovedDefinition",
        "docurl": "https://github.com/Azure/openapi-diff/tree/master/docs/rules/1006.md"
      }
    ],
    "warnings": [],
    "info": []
  }
}

String Format
Old Output

code = NoVersionChange, type = Info, message = The versions have not changed.
code = RemovedDefinition, type = Error, message = The new version is missing a definition that was found in the old version. Was 'DatabaseList' removed or renamed?

Modified Output

additions : errors = [], warnings = [], info = []; updates : errors = [], warnings = [], info = [code = NoVersionChange, message = The versions have not changed., docurl = https://github.com/Azure/openapi-diff/tree/master/docs/rules/1001.md]; removals : errors = [code = RemovedDefinition, message = The new version is missing a definition that was found in the old version. Was 'DatabaseList' removed or renamed?, docurl = https://github.com/Azure/openapi-diff/tree/master/docs/rules/1006.md], warnings = [], info = []

[billytrend]

wouldn't it be easier to just dump json here? or are you doing this for a better UX?

[sarangan12]

This PR is no longer required.