Make it easier to do graceful shutdown with axum 0.7

[davidpdrsn]

Most of the work is done (#2398) but currently blocked by PRs for hyper and hyper-util.

[wangziling]

Hmmm... Hi David~

Does this PR can solve this?

Seems the .call only be applied on Router<()>. 😞

And call_with_state is a crate-visible-only fn.

[davidpdrsn]

No that is unrelated. Please open a separate discussion about it.

[wangziling]

Hi David. Leave it alone. My apologize, I forgot to use .with_state(). 😞

[davidpdrsn]

#2398 has been shipped in axum 0.7.3 🎉