Owner address in Reshare struct can be removed

[alan-ssvlabs]

The Reshare struct is used for an initiator to start a reshare, specifying the parameters including validatorPubKey, oldOperators, newOperators, oldThreshold, newThreshold, for, withdrawalCredentials, owner, nonce.

However, the owner here is not really necessary as the owner address is also included in Proofs, that are also required to present when starting reshare.

[GalRogozinski]

In ValidateCeremonyProof it seems like we need it @alan-ssvlabs

dkg-spec/proof.go

Lines 16 to 18 in 2f5e6b6

	if !bytes.Equal(ownerAddress[:], signedProof.Proof.Owner[:]) {
	return fmt.Errorf("invalid owner address")
	}

If you agree I can close this

[alan-ssvlabs]

Not really agree. We can safely remove this check as well if we remove the owner address in Reshare. By doing that we are simply removing a place where initiator can mess things up. @GalRogozinski

The purpose of this check is to make sure whether the owner address in the Reshare correct (same as the one in Proofs). It is unnecessary because anyway operators can directly uses the owner address in Proofs to understand who is the owner.