Add new index-type ecs to support ecs formatted index name for metrics, logs, etc.

Is your feature request related to a problem? Please describe.
Add new index-type ecs to support ecs formatted index name for metrics, logs, etc. based on the naming scheme mentioned here -
https://www.elastic.co/blog/an-introduction-to-the-elastic-data-stream-naming-scheme

Describe the solution you'd like
I think the following solution is simple and easy
Add new index type to the existing index-types in opensearch sink

     index-type: ecs
     # index-name: <type>-<dataset>-<namespace>
     index-name: metrics-ngnix.access-xyz

Describe alternatives you've considered (Optional)
Alternative approach is

     index-type: ecs
     type-name: metrics
     dataset-name: ngnix.access
     namespace-name: xyz

Additional context
Need to create an index mapping for different types. To start with, index mapping for histogram metric type should be created as per OTEL format

Start in the OpenSearch sink's existing index-type handling and review the linked Elastic data-stream naming scheme. Define how the ecs type should produce the requested metrics, logs, and related names, then verify the histogram metric mapping follows the stated OTEL format.