Revisit the match type in extra-file-input case

[kuzdogan]

From the discussion in ethereum/solidity#14250 that is a similar bug to #618, I notice we might be verifying the contracts "perfectly" in a wrong way.

This is because when we compile with extra files the metadata file would have been changed, and the hashes wouldn't match. However, in the implementation (ie. useAllSources) we are creating the CheckedContract with the old metadata (with the original sources) but with the sources + extra files. The generated Solidity JSON has files that are not present in the metadata.

That means the compilation is not reproducible.

_{View in Huly HI-474}