chore: refactor -copy common code #4332

Job	Run time
check	18s
check no_std	1m 3s
check serde	31s
check no_std kzg-rs	27s
clippy	1m 20s
check std	38s
docs	59s
fmt	4s
test stable --no-default-features	54s
TyposCheck	5s
test stable	53s
test stable --all-features	1m 15s
test beta --no-default-features	1m 21s
test beta	54s
test beta --all-features	1m 13s
test nightly --no-default-features	52s
test nightly	1m 4s
test nightly --all-features	1m 7s
	14m 58s

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