Sourcify support

Hi, just encountered the project randomly and really liked it. It is in lines with what we are trying to achieve at https://sourcify.dev.

Sourcify is a decentralized verified contract repository and an open-sourced smart contract verification tool. We pin the Solidity metadata files and source files on IPFS, which are retrievable through the bytecode ([See in action in the playground](https://playground.sourcify.dev/)).

We also want to make it easier for the users to do "edge verification" because while getting contracts from IPFS through the bytecode is convenient, one still needs to make sure the source code behind the IPFS CID really compiles to this code. Although really unlikely, the contract deployer can still tamper with the CID that is normally placed by the Solidity compiler.

Would love to see native Sourcify support on evmc. Let me know how we can help, and happy to chat!

cc: @marcocastignoli