[FEATURE] Make raw JSON REST requests to OpenSearch

[dblock]

Is your feature request related to a problem?

Coming from opensearch-project/opensearch-clients#62, add support for making raw JSON requests.

What solution would you like?

1. Document transport.request, similar to Added a guide on making raw JSON REST requests. opensearch-py#542. See Add support for security and other API requests #264 (comment) for an example.
2. Add a high level DSL, e.g. client.get and client.post.

[AbhinavGarg90]

I'd love to pick this issue up if it is available @dblock.

[dblock]

All yours @AbhinavGarg90