Configure Max Header Count

• I have looked for existing issues (including closed) about this

Feature Request

Motivation

Working on a large enterprise system and using axum for one of our services. The system, for better or worse, passes around a large number of headers, over the default number of 100 headers as declared in hyper.

The hyper library exposes a function to override this default value, however this is not exposed through axum.

Proposal

Expose this configuration through axum configuration settings.

Would you be receptive to a pull request to expose this as a config option?

Alternatives

We maintain a patched fork to set this in serve.rs, but would rather have this configurability present in the unpatched library.

We considered using plain hyper, which is suggested in the axum docs, however such a relatively innocuous http-server configuration seems valid for inclusion in axum configuration.