feat(cast): support short cut for querying erc20 balance in cast balance

[fenghaojiang]

Motivation

Closes #6813

As erc20 / erc721 standards become common sense, I want to make a short cut to query erc20 / erc721 balance without having to write following script:

cast call [token_address] "balanceOf(address) returns uint256" --rpc-url=https://rpc.ankr.com/eth 

After this PR:
querying erc20 balance would be easier. like:

cast balance 0x162c6270266667ccf5a9ed752b5d6a2bdc0f90de --token=0x5a98fcbea516cf06857215779fd812ca3bef1b32  --rpc-url=https://rpc.ankr.com/eth

And support ENS:

cast balance vitalik.eth --token=0x4e3fbd56cd56c3e72c1403e103b45db9da5b9d2b  --rpc-url=https://rpc.ankr.com/eth

The original cast balance remains unchanged.

cast balance birdring.eth  --rpc-url=https://rpc.ankr.com/eth

After new option --token added into cast balance --help:

Get the balance of an account in wei

Usage: cast balance [OPTIONS] <WHO>

Arguments:
  <WHO>
          The account to query

Options:
  -B, --block <BLOCK>
          The block height to query at.

          Can also be the tags earliest, finalized, safe, latest, or pending.

  -e, --ether
          Format the balance in ether

  -r, --rpc-url <URL>
          The RPC endpoint

          [env: ETH_RPC_URL=]

      --flashbots
          Use the Flashbots RPC URL (https://rpc.flashbots.net)

      --jwt-secret <JWT_SECRET>
          JWT Secret for the RPC endpoint.

          The JWT secret will be used to create a JWT for a RPC. For example, the following can be used to simulate a CL `engine_forkchoiceUpdated` call:

          cast rpc --jwt-secret <JWT_SECRET> engine_forkchoiceUpdatedV2 '["0x6bb38c26db65749ab6e472080a3d20a2f35776494e72016d1e339593f21c59bc",
          "0x6bb38c26db65749ab6e472080a3d20a2f35776494e72016d1e339593f21c59bc", "0x6bb38c26db65749ab6e472080a3d20a2f35776494e72016d1e339593f21c59bc"]'

          [env: ETH_RPC_JWT_SECRET=]

  -t, --token <TOKEN>
          Token address to query, with the method `balanceOf(address) return (uint256)`

  -h, --help
          Print help (see a summary with '-h')

Solution

The solution is in the branch if --token option is not empty and the original cast balance remains unchanged.

[fenghaojiang]

Problems resolved as you requested. Plz review the code again.

[DaniPopes]

Thanks!