OpenAPI: Codegen improvements

[ademange-legion]

Summary

Improve the openapi codegen to better support our needs.

Work Items

• [x] Ability to serve multiple APIs in a single HTTP server.
• [x] Regroup request arguments in a dedicated type to better support defaults.
• [x] Replace reqwest by hyper client library for better access to HTTP Parts
• [x] Add mutable Context arg to access / edit request and response infos
• [x] Add axum ConnectInfo extractor
• [x] Add codegen test crate to validate compilation