rusk: implement RuskHttp builder and shutdown

[Neotamandua]

Closes #2453

Fixes the panic messages in tests when running:
cargo test --release --lib http::tests -- --nocapture

[Copilot]

Pull request overview

This PR implements a builder pattern for RuskHttp with proper shutdown handling, addressing test panic messages. The changes restructure the HTTP server to support graceful shutdown with configurable timeouts and eliminate a redundant runtime.

Changes:

• Added RuskHttp struct with run() and shutdown() methods to manage HTTP server lifecycle
• Modified HttpServer to support graceful shutdown by making wait() consume handle once and adding shutdown() method
• Removed nested tokio runtime in listening_loop that was causing shutdown issues

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
rusk/src/lib/http.rs	Changed HttpServer fields to Option types and added shutdown() method; removed nested runtime from listening_loop
rusk/src/lib/builder/http_only.rs	Added RuskHttp struct with lifecycle methods and enhanced builder with data source and timeout configuration

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[HDauven]

I would approve this PR, but the removal of the dedicated HTTP runtime in listening_loop slightly concerns me.

HTTP connections now share the main runtime via task::spawn, resulting in heavy HTTP/RUES traffic potentially starving consensus. We should keep separate runtimes for chain mode or add concurrency limiting in my opinion. Consensus/core chain should always have priority over anything else.

What do you think @herr-seppia?