Move all Solidity 0.6.12 Files to Artifact Files

[ElliotFriedman]

Instead of needing three different compiler versions, 0.6.12, 0.8.10 and 0.8.19, we can eliminate needing to compile with 0.6.12 by saving the compiled artifacts to the repository. This should speed compile times as now only two Solidity versions will be needed. This will allow us to remove safety module tests, which is fine because this code will not be changing anymore.

In order to accept this change, we should verify across 3 separate machines that the artifacts match before finalizing this change.