[Feature] Datastream lifecycle

[aizerin]

In my previous PR #724, I added support for the DS template lifecycle. However, this is insufficient to update the existing DS lifecycle.

https://www.elastic.co/guide/en/elasticsearch/reference/current/tutorial-manage-existing-data-stream.html

I can implement new resources for these APIs

https://www.elastic.co/guide/en/elasticsearch/reference/current/data-streams-get-lifecycle.html
https://www.elastic.co/guide/en/elasticsearch/reference/current/data-streams-put-lifecycle.html
https://www.elastic.co/guide/en/elasticsearch/reference/current/data-streams-delete-lifecycle.html

usage would be:

resource "elasticstack_elasticsearch_data_stream_lifecycle" "ds_lifecycle" {
  name = "ds-name"
  data_retention = "5d"
  enabled = true
  downsampling=[...]
}

Is it OK for you to do it this way?

[tobio]

Sounds perfect @aizerin!