Add BLS12-381 verification

[SilentCicero]

Abstract

Barreto-Lynn-Scott ("BLS") signature verification will become more important for Fuel as we deploy to data constrained environments like Ethereum. In this PR we define a BLS signature verification operation for the Fuel Virtual Machine.

This operation allows three modes: singular, aggregate and special aggregate verification of BLS12-381 signatures.

Proposed Modes

1. Single signature verification - signature, message and public key are in memory
2. Aggregate verification - signatures, messages, and public keys are in memory

Would request HashCloak to writeup the cryptographic specifics in the cryptography section of the specifications.