Prototype GGLWE CMUX for BDD circuits

[Janmajayamall]

Prototype retrieval of GGLWE ciphertexts from RAM, followed by op using BDD circuit, and write the GGLWE ciphertext back to the RAM.

The benefit of using GGLWE ciphertext by default is that it saves circuit bootstrapping. Because, GGLWE(m) -> GGSW(m) is simple key switch (sorta): GGLWE(m) x GGLWE(s^2).