Add errors to updateStatus Class

[eskombro]

An update status contains, in case of failure, relevant information about the error (message, code and a link to the description of the error in the docs) that should be added to the UpdateStatus for further usage in this SDK and for users!

Example of a failed update:

{
"status":"failed",
"updateId":1,
"type": {
  "name":"DocumentsAddition",
  "number":2
},
"duration":2.55E-5,
"enqueuedAt":"2020-09-28T20:17:27.005486800Z",
"processedAt":"2020-09-28T20:17:27.016900700Z",
"errorCode":"missing_document_id",
"errorType":"invalid_request_error",
"errorLink":"https://docs.meilisearch.com/errors#missing_document_id"
}