Rust SDK: Add dedicated TCP/TLS examples

[mmodzelewski]

Summary

The Rust SDK has comprehensive TCP/TLS support (using `rustls`/`tokio-rustls`) and integration tests exist at the server level (`core/integration/tests/server/scenarios/tcp_tls_scenario.rs`), but there are no dedicated TLS examples in `examples/rust/`.

Current State

• TLS implementation: Full support in `core/sdk/src/tcp/`:
  • `tcp_tls_connection_stream.rs` - TLS connection stream
  • `tcp_tls_verifier.rs` - Custom TLS certificate verifier
  • `tcp_client.rs` - Client with TLS support
  • Also WebSocket TLS and QUIC TLS support
• Integration tests: Server-level TLS scenario exists in `core/integration/tests/server/scenarios/tcp_tls_scenario.rs` that tests stream/topic creation, message send/receive over TLS
• Examples: CLI args in `examples/rust/src/shared/args.rs` support `--tcp-tls-enabled`, `--tcp-tls-domain`, `--tcp-tls-ca-file` flags, but there is no dedicated TLS example showing how to use them. Users need to discover these flags themselves.

Requirements

Examples

• Add a dedicated TLS example in `examples/rust/` demonstrating:
  • How to configure `IggyClientBuilder` with TLS options (enabled, domain, CA file)
  • How to use custom certificates from `core/certs/` (`iggy_ca_cert.pem`, `iggy_cert.pem`, `iggy_key.pem`)
  • A simple producer/consumer flow over TLS
  • Include instructions in comments/README for how to start the server with TLS enabled
• Alternatively or additionally, document the TLS CLI flags usage with an example command in the existing examples

Reference

• TLS implementation: `core/sdk/src/tcp/tcp_tls_connection_stream.rs`
• Existing TLS scenario test: `core/integration/tests/server/scenarios/tcp_tls_scenario.rs`
• CLI args with TLS flags: `examples/rust/src/shared/args.rs`
• Server TLS config env vars: `IGGY_TCP_TLS_ENABLED=true`, `IGGY_TCP_TLS_CERT_FILE`, `IGGY_TCP_TLS_KEY_FILE`
• Custom certs location: `core/certs/`

[atharvalade]

I'd like to work on this issue.