Add mTLS support

[KunoVonHagen]

This pull request introduces comprehensive support for TLS (including mutual TLS) in the CI pipeline and the FluvioWriter plugin initialization. The main focus is to ensure secure communication when interacting with Fluvio by configuring and testing TLS parameters both in automated workflows and at runtime, while maintaining backward compatibility for non-TLS environments.

CI/CD and TLS Integration:

• Added a new GitHub Actions workflow (.github/workflows/ci-tls.yml) that sets up a full end-to-end CI pipeline for testing the Zeek plugin with TLS/mTLS enabled Fluvio clusters. This includes generating certificates, starting a Fluvio cluster with TLS, and running integration tests.

Plugin Runtime TLS Configuration:

• Updated FluvioWriter::DoInit in src/FluvioWriter.cc to dynamically detect TLS configuration from environment variables (FLUVIO_TLS_DOMAIN, FLUVIO_TLS_KEY, FLUVIO_TLS_CERT, FLUVIO_TLS_CA). If present, the plugin configures strict mTLS; otherwise, it falls back to a non-TLS connection, improving flexibility and security.
• Modified Fluvio client initialization to use the new TLS-aware configuration, ensuring the plugin can securely connect to Fluvio clusters when required.

[stefanDeveloper]

Finally tls :)

[stefanDeveloper]

fixed #1