enhancement: Support Phased Releases

[Sherlouk]

https://developer.apple.com/documentation/appstoreconnectapi/app_store_version_phased_releases

For our use case we need to be able to load the phased release information for a given version of the app (the URL is available through a relationship link but no data).

GET https://api.appstoreconnect.apple.com/v1/appStoreVersions/UUID/appStoreVersionPhasedRelease

{
  "data": {
    "type": "appStoreVersionPhasedReleases",
    "id": "UUID",
    "attributes": {
      "phasedReleaseState": "ACTIVE",
      "startDate": "2020-12-14T10:16:45Z",
      "totalPauseDuration": 0,
      "currentDayNumber": 1
    },
    "links": {
      "self": "https://api.appstoreconnect.apple.com/v1/appStoreVersionPhasedReleases/UUID"
    }
  },
  "links": {
    "self": "https://api.appstoreconnect.apple.com/v1/appStoreVersions/UUID/appStoreVersionPhasedRelease"
  }
}

[github-actions]

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[Sherlouk]

Done in #127