feat: implement hash_to_G1 function for bls12-381

[feltroidprime]

Hashing to the curve is needed to verify bls signatures.
An example of implementation can be found here https://github.com/ConsenSys/gnark-crypto/blob/f93a56c714c4e6266429cac111a004e9eec7daa0/ecc/bls12-381/hash_to_g1.go#L313