Extractors: generate standard input for Sourcify contracts from metadata

[rimrakhimov]

requires: #632

Currently implemented blockscout extractor does not process contracts verified via Sourcify. The problem is that sometimes file paths are irreversibly mangled when the files obtained through the Sourcify verification. We need a way to bypass it somehow.

Besides, that may be a good starting point to understand how we can re-verify smart-contracts verified via Sourcify ourselves, so that we can use that contracts for further processing inside eth-bytecode-db.

The details of the mangling issue: blockscout/blockscout#7648.

Discussion in Sourcify repo and their solution: ethereum/sourcify#515

[rimrakhimov]

It probably does not make sense to implement such conversion right now, as we are in the process of moving to Verifier Alliance Database. Sourcify team has said that they are going to re-verify those contracts and insert them into the shared database anyway