feat: expose HTTP/1.1 parsing API for raw byte parsing

[AdamDawidKrol]

Is your feature request related to a problem?
I need to parse raw HTTP/1.1 bytes from TLS transcripts (for TLSNotary/web proofs). hyper has robust parsing internals, but they're only accessible through the async connection layer. I can't use them for offline byte parsing.

Describe the solution you'd like
Expose a minimal parsing API (perhaps behind a feature flag):

use hyper::proto::h1::{ServerTransaction, Http1Transaction, ParseContext};
let parsed = ServerTransaction::parse(&mut bytes, ctx)?;
// Access: parsed.head.subject (method, uri), parsed.

Already considered

• httparse directly — works but loses hyper's header normalization, keep-alive detection, chunked/content-length handling
• Fork hyper — currently doing this at vlayer-xyz/hyper, but maintenance burden

Additional context
Use case: TLSNotary and similar projects record TLS sessions via MPC. We need to parse the resulting HTTP transcript bytes to extract headers/body for verification, without re-implementing hyper's parsing logic.

[seanmonstar]

Hey there! So, I'll start saying I feel hesitant. I don't think I want to solidify the internal HTTP/1 design publicly...

But, what exactly are you hoping to get from such an API? The various doodads in there are more for hyper's internal bookkeeping, it wouldn't get you automatic keep-alive or body length handling, from what I can tell. You'd need to keep calling the internals incrementally...