Make Proof.verify inside a circuit work from serialized compile output

[mitschabaude]

It would be nice if we wouldn't have to recompile ZkProgram dependencies, but could serialize the compiled output to a file and recreate everything that's necessary for verifying inside circuits just from that file

this is already possible for verifying outside the circuit, where the serialization is the base58 verification key

probably similar to #87 and could be tackled in one sprint with that issue