Design a better serialization strategy

[ChihChengLiang]

In a client server interaction, we need to pass data like server key shares, FheUint8 outputs, and decryption shares.

We should have some ways to serialize them.

#3 is a quick and dirty way to fix this problem. We derive Serde traits to structs, then use bincode::serialize to serialize it for minimum data size.

Design consideration and challenges:

• server key shares CommonReferenceSeededNonInteractiveMultiPartyServerKeyShare is 226 MB. We might want to reduce the size of this struct.
• FheUint8 and decryption shares are inherently Vec. So simple Serde might already be enough.