Add Hardhat and Foundry build-info file support for verify.sourcify.dev

[kuzdogan]

Following up from oasisprotocol/docs#1355 and my chat today with @FlorianDr it seems actually importing Hardhat and Foundry files is useful for users. Hardhat, because actually Sourcify verification requires downloading the hardhat-verify plugin... Foundry, because it isn't possible to pass creatorTxHash on foundry CLI.

It should also be quite straightforward to implement this. Just take the "input" field, language, and compiler versions from the build-info files.

TODO:

• Update the "How to Verify Docs"

[Patrick-Ehimen]

@kuzdogan i would like to be assigned this issue