Expose commit SHA in PR reviews JSON export - #6646

$ gh pr view 6603 --json reviews                       
{
  "reviews": [
    {
      "id": "PRR_kwDODKw3uc5GR6yX",
      "author": {
        "login": "mislav"
      },
      "authorAssociation": "MEMBER",
      "body": "Thanks for taking this on! Let's use YAML as it's more readable in its raw format than JSON.",
      "submittedAt": "2022-11-14T13:24:00Z",
      "includesCreatedEdit": false,
      "reactionGroups": [],
      "state": "CHANGES_REQUESTED",
      "commit": {
        "oid": "2e0e229d481b65c6302ec06225196a115b3fa5f4"
      }
    }
  ]
}