Support for multicall3

So viem in its chain definitions has multicall3 address. I think this would be helpful for alloy chains definitions also. Multicall3 address are already fairly standardised in most popular chain (checkout https://www.multicall3.com/)
Example of a viem chain with multicall3 address
```
import { defineChain } from '../../utils/chain/defineChain.js'

export const dogechain = /*#__PURE__*/ defineChain({
id: 2_000,
name: 'Dogechain',
nativeCurrency: {
decimals: 18,
name: 'Wrapped Dogecoin',
symbol: 'WDOGE',
},
rpcUrls: {
default: { http: ['https://rpc.dogechain.dog'] },
},
blockExplorers: {
default: {
name: 'DogeChainExplorer',
url: 'https://explorer.dogechain.dog',
apiUrl: 'https://explorer.dogechain.dog/api',
},
},
contracts: {
multicall3: {
address: '0x68a8609a60a008EFA633dfdec592c03B030cC508',
blockCreated: 25384031,
},
},
})
```

PS: I am down to work on this!