der: impl `RefToOwned`/`OwnedToRef` for `&[u8]`/`Box<[u8]>` #2431

Job	Run time
build (1.65.0, thumbv7em-none-eabi)	2m 6s
build (1.65.0, wasm32-unknown-unknown)	2m 46s
build (stable, thumbv7em-none-eabi)	54s
build (stable, wasm32-unknown-unknown)	48s
test (1.65.0)	3m 32s
test (stable)	2m 8s
minimal-versions / minimal-versions	2m 19s
	14m 33s

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