* Improve compile times of `handle_error`
This brings the compile time of the example posted [here][example] from
3 seconds down to 0.3 seconds for me.
Having the bounds on the methods does improve UX but not worth
sacrificing 10x compile time for.
[example]: https://github.com/tokio-rs/axum/issues/145#issue-963183256
* Improve compile time of `check_infallible`
* update changelog
They'd previously see the nested URI as we mutated the request. Now we
always route based on the nested URI (if present) without mutating the
request. Also meant we could get rid of `OriginalUri` which is nice.