Add support for routing shorthand. #4099

Job	Run time
cargo-hack	3m 18s
check	2m 16s
cargo-public-api-crates (axum)	59s
check-docs	21s
cargo-public-api-crates (axum-core)	52s
dependencies-are-sorted	43s
cargo-public-api-crates (axum-extra)	1m 0s
cargo-deny check (advisories)	25s
cargo-public-api-crates (axum-macros)	49s
cargo-deny check (bans licenses sources)	22s
Spell Check with Typos	7s
test-nightly	1m 51s
test-docs	1m 44s
test-versions (stable)	2m 40s
test-msrv	1h 50m 5s
test-versions (beta)	5m 8s
armv5te-unknown-linux-musleabi	58s
wasm32-unknown-unknown	20s
	2h 13m 58s

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