Migrate Dpos/Address Mapper to using EIP712

[mattkanwisher]

    const hash = soliditySha3(
      {
        type: 'address',
        value: from.local.toString().slice(2)
      },
      { type: 'address', value: to.local.toString().slice(2) }
    )
    console.log("addIdentityMappingAsync-hash-", hash)
    const sign = await ethersSigner.signAsync(hash)

Appears we started out with a very similar scheme to eip712. We now need to switch to full standard cause Ethers.js doesn't support eth_personal_sign method except on metamask, so it breaks on things like TrustWallet