implement bls12-381 functions #4274

Job	Run time
check-git-rev-deps	8s
build-fuzz	3m 32s
build-and-test (msrv, ubuntu-latest, x86_64-unknown-linux-gnu)	13m 58s
cargo-deny (advisories)	49s
build-and-test (msrv, ubuntu-latest, aarch64-unknown-linux-gnu, true)	8m 44s
cargo-deny (bans licenses sources)	48s
build-and-test (msrv, windows-latest, x86_64-pc-windows-msvc)	21m 6s
fmt	4s
docs	6m 1s
build-and-test (latest, ubuntu-latest, x86_64-unknown-linux-gnu)	14m 15s
publish-dry-run	0s
build-and-test (latest, ubuntu-latest, aarch64-unknown-linux-gnu, true)	8m 25s
semver-checks	5m 35s
build-and-test (latest, windows-latest, x86_64-pc-windows-msvc)	21m 1s
readme	5m 28s
complete	1s
	1h 49m 55s

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