[contract-deploy] Verify executed bytecode in PXE

[spalladino]

The PXE should use the address' class.artifactHash to check that the bytecode it's going to execute matches the intended one. This check should be done either before calling the simulator, or when a new contract artifact is added to the PXE.

[spalladino]

Not required. The PXE computes the class id from the entire artifact hash, which includes private function bytecode. Changing the bytecode would change the class id.