abigen adopt hardhat generated bytecode

[zsluedem]

Motivation

The hardhat compiled artifacts are like below

{
  "abi":[...],
  "bytecode": "..."
}

And the current ethers-rs could only support {"abi": [..], "bin": "..."} or {"abi": [..], "bytecode": {"object": "..."}}.

Solution

PR Checklist

• Added Tests
• Added Documentation
• Updated the changelog
• Breaking changes

[gakonst]

Am OK with this - @mattsse ?

[mattsse]

while this adds support for hardhat, it no longer supports the nested object format, right?

instead of removing the "bytecode": {"object": "..."} case, we should keep it and just add bytecode": "0x00000000" as an additional variant instead.

[mattsse]

nvm I totally misread that, that's already the case, sorry for the confusion

lgtm