CreateIndex doesn't return index name

[octocat-mona]

NEST/Elasticsearch.Net version:
6.8.0

Elasticsearch version:
6.8.0

Describe the feature:
Currently CreateIndexAsync returns an ICreateIndexResponse which includes the ShardsAcknowledged and Acknowledged properties but not the index name as returned in the json response:

{
  "acknowledged" : true,
  "shards_acknowledged" : true,
  "index" : "my-index-2019.06.17-000001"
}

This is useful when indices are created using Date Math patterns like %3Cmy-index-%7Bnow%2Fd%7D-000001%3E so the date doesn't has to be calculated again.

[codebrain]

PR merged, will be in next release.