Update methods to create `FromFnLayer` (#2966) #4917

Job	Run time
check	1m 30s
cargo-hack	4m 51s
cargo-public-api-crates (axum)	29s
cargo-public-api-crates (axum-core)	19s
cargo-deny check (advisories)	26s
cargo-public-api-crates (axum-extra)	29s
check-docs	26s
cargo-deny check (bans licenses sources)	28s
dependencies-are-sorted	12s
cargo-public-api-crates (axum-macros)	18s
Spell Check with Typos	4s
test-nightly	1m 56s
test-versions (stable)	2m 54s
test-docs	1m 43s
test-versions (beta)	2m 36s
armv5te-unknown-linux-musleabi	47s
test-msrv	1m 51s
wasm32-unknown-unknown	18s
	21m 37s

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