Add Api definitions for create, get, and delete data_stream

[nhtruong]

This is part of the index_management plugin that have now been added to OS as core features in the indices namespace, so the operation groups of these actions would be
indices.create_data_stream
indices.get_data_stream
indices.delete_data_stream

https://opensearch.org/docs/latest/im-plugin/data-streams/

[Tokesh]

I'd like to work on this issue :)
I'm already read this article about data streams. I think i have only one question about create_data_stream API.
In article they gave us such examples:
PUT _data_stream/logs-redis
PUT _data_stream/logs-nginx
Are "logs-redis" and "logs-nginx" just indexes, not index_templates?

[nhtruong]

A data stream is internally composed of multiple backing indexes. Search requests are routed to all the backing indexes, while indexing requests are routed to the latest write index.

So it makes sense that you need an index_template (it's like grepping for indices with similar names) to create a data-stream, since a data-stream is a collection of indices.

[nhtruong]

@Tokesh Looks like even though these endpoints were part of the legacy index_management plug-in. They have been added to OS as core features of the indices namespace. I've update the Issue's description to reflect that.

[Tokesh]

So it makes sense that you need an index_template (it's like grepping for indices with similar names) to create a data-stream, since a data-stream is a collection of indices.

@Tokesh Looks like even though these endpoints were part of the legacy index_management plug-in. They have been added to OS as core features of the indices namespace. I've update the Issue's description to reflect that.

Thank you so much for answers. I got it!

[Xtansia]

Closing as #131 was merged