FIPS 140-3 support in OpenSearch

OpenSearch 3.6 introduces native FIPS 140-3 support, enabling the platform to meet the strict cryptographic requirements of highly regulated sectors such as government, finance, and healthcare. Developed through a multi-year collaboration between SAP, SAS, and AWS, this update ensures all internal cryptographic operations use validated modules and approved algorithms. Administrators can activate this compliance mode in the standard distribution by setting the `OPENSEARCHFIPSMODE=true` environment variable.