Use ArkWorks BLS12-381 implementation

[annenkov]

Task description

Change the BLS12-381 curve implementation to https://crates.io/crates/ark-bls12-381
Currently, we use the BLS12-381 curve implementation from an outdated version of the pairing crate. Updating this implementation is not possible because the target group type is not accessible externally and we need it to define custom serialization (see the details here).
ArkWorks ecosystem offers many curve implementations and is well-maintained.

However, in order to use an up-to-date version of ArkWorks' BSL12-381, we need to update ed25519-dalek, since the versions of rand crate must agree. It's also desirable to do so due to the security advisory related to the version of the crate before 2.0.

Both changes (ArkWorks BLS and ed25519-dalek upgrade) should happen at the same time.

Sub-tasks

• Define adapters to ArkWorks algebra traits
• Integrate the BLS21-381 curve implementation
• Upgrade ed25519-dalek to version 2.