Malformed BinFHEContext archive can trigger a heap-buffer-overflow in RingGSWCryptoParams::PreCompute

Just like in [Question / parser robustness report] BFVrns ciphertext deserialization can reach impractical allocation requests from malformed ciphertext metadata - #2 by ypolyakov, our focus is on the honest-but-curious model. The issues dealing with malicious adversaries are not our primary focus because FHE is typically instantiated under the honest-but-curios model.