der: conversions from `OctetString(Ref)` to `Vec`/`Bytes` #1035

Job	Run time
build (1.81.0, thumbv7em-none-eabi)	23s
test (1.81.0)	25s
build (1.81.0, wasm32-unknown-unknown)	28s
build (stable, thumbv7em-none-eabi)	18s
test (stable)	17s
build (stable, wasm32-unknown-unknown)	23s
minimal-versions	0s
	2m 14s

Provide feedback