add multitenant support for search workloads

[kaushalmahi12]

Description

This PR add support to add labels to support multitenancy in opensearch. These labels can be consumed by any feature e,g; Query Sandboxing, Query Insights, Slow logs etc;

Sample search request body to pass these labels

curl -X GET "localhost:9200/my-index-*/_search?size=1000&pretty" -H 'Content-Type: application/json' -d '{
  "query" : {
  },
  "labels": {
    "tenant": "analytics"
  }
}'

Related Issues

https://github.com/opensearch-project/OpenSearch/issues/12342

Check List

• [X] New functionality includes testing.
  • [X] All tests pass
• [] New functionality has been documented.
  • [X] New functionality has javadoc added
• [ ] API changes companion pull request created.
• [ ] Failing checks are inspected and point to the corresponding known issue(s) (See: Troubleshooting Failing Builds)
• [X] Commits are signed per the DCO using --signoff
• [ ] Commit changes are listed out in CHANGELOG.md file (See: Changelog)
• [ ] Public documentation issue/PR created

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