Do Trung Kien

`ds-test` now is included in`forge-std`, which is the standard test library of forge. replace `ds-test` with `forge-std` will make the code shorter and up to date with foundry. Reference: https://book.getfoundry.sh/reference/forge-std/

use web3.eth.personal.sign instead of web3.eth.sign in Web3Signer

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is there any way to use `web3.eth.personal.sign` instead of `web3.eth.sign` in [Web3Signer](https://github.com/loomnetwork/loom-js/blob/master/src/solidity-helpers.ts#L73) what i want is to use [addIdentityMappingAsync](https://github.com/loomnetwork/loom-js/blob/master/src/contracts/address-mapper.ts#L32) with a **custom** sign message instead of a hash with warning...