Deprecate SHA-1 and MD5 from Fluent Bit code paths

**Is your feature request related to a problem? Please describe.**
Fluent Bit currently contains a small number of SHA-1 and MD5 code paths.

Some MD5 usages are required for interoperability with external services (for example, cloud-provider APIs that mandate MD5-based integrity checks) and therefore cannot be removed without breaking compatibility.

The remaining SHA-1 usage appears to be limited primarily to legacy operations such as X.509 certificate fingerprint generation (for example, via X509_digest) rather than security-sensitive operations like authentication, digital signatures, or TLS certificate validation.

Although these usages do not present an immediate security vulnerability, both SHA-1 and MD5 are considered legacy cryptographic algorithms and are increasingly flagged by security scanners, compliance frameworks, and FIPS-oriented environments. Their presence often results in unnecessary compliance findings even when they are only used for non-security purposes.

**Describe the solution you'd like**
- **Phase1:** all new functionality should use SHA-256 (or stronger algorithms where appropriate)
- **Phase2**: the existing SHA-1/MD5 implementation is retained only for backward compatibility with warning messages like "_SHA1/MD5 is going to deprecate in the future_"
- **Phase3**: evaluate and enable support for newer cloud provider checksum mechanisms: Newer cloud-provider APIs that can use stronger checksums (**e.g., SHA-256 for AWS S3, CRC64 for Azure Blob Storage**)
- **Phase4**: remove SHA-1 and MD5 implementations from Fluent Bit completely when all external dependencies have officially deprecated them.

This would reduce compliance findings while keeping Fluent Bit fully compatible with existing integrations.