Refactor Fluvio C++ Client API to Modern Object-Oriented Design with Updated Rust Internals and C API

[KunoVonHagen]

This pull request refactors the C++ client API for Fluvio to provide a more idiomatic, object-oriented interface, aligning it with the original Fluvio client. The changes affect both the Rust internals and the C++/C API surface, and update all documentation and examples to use the new API. The result is a cleaner, more intuitive experience for C++ users, with improved consistency and maintainability.

API Refactoring and Object-Oriented Interface:

• Replaced procedural C-style functions (e.g., fluvio_connect, create_producer, producer_send) with object-oriented methods on Fluvio, FluvioAdmin, TopicProducerPool, and FluvioStream classes. For example, Fluvio::connect(), client->topic_producer(...), producer->send(...), and stream->next() are now used throughout the API and examples. [1] [2] [3] [4] [5]

• Updated the internal Rust implementation to match the new API, renaming types and methods (e.g., FluvioClient → Fluvio, FluvioProducer → TopicProducerPool, FluvioRecord → Record) and moving procedural functions to associated methods. [1] [2]

Documentation and Examples:

• Revised all documentation (README.md, examples/README.md) to use the new object-oriented API, including code snippets and explanations. Added an API mapping section for clarity. [1] [2] [3] [4] [5] [6]

• Refactored example programs (examples/producer.cpp, examples/consumer.cpp) to use the new API, improving readability and demonstrating best practices. [1] [2] [3]

C API and Configuration:

• Updated the C API to use new types and methods, and simplified configuration handling by removing the wrapper struct in favor of direct use of FluvioConfig. All related functions and memory management routines were updated accordingly. [1] [2] [3]

Other Improvements:

• Minor build and workflow improvements in documentation (e.g., adding cd .. after tests).

These changes collectively modernize the C++ client API, making it more maintainable and easier for users to understand and use.

[stefanDeveloper]

Looks good from my side.

[stefanDeveloper]

Keep in mind that we have to update https://github.com/stefanDeveloper/zeek-fluvio