[FEATURE] Deprecate hand-coded index_management in favor of auto-generated ism.

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Is your feature request related to a problem?

Coming from #830, the OpenSearch API spec has added ISM in opensearch-project/opensearch-api-specification#568. However opensearch-py already has index_management (different name) and the auto-generated implementation is not compatible because it re-orders body and index parameters.

What solution would you like?

1. Add support for reordering parameters in api generator and swap index and body in the case of ISM for backwards-compat.
2. Deprecate IndexManagementClient and implement it by inheriting auto-generated IsmClient instead.

What alternatives have you considered?

A breaking change where we delete IndexManagementClient and use the generated IsmClient.