Update serialization to use serde

[piotr-roslaniec]

• There is no direct compatibility with serde, although some exploratory work is being done in this area
• Trying to create a workaround for that using serde_with and changes from the already-merged PR at arkworks. So far no luck. Tracking this work here.
  • Update: Decided to postpone this work since it requires updating a host of arkworks ecosystem crates.
• This issue is hence blocked by the 0.4 version release of arkworks/algebra crates, and the subsequent release of the updated arkworks-bls-12-381 crate

[mimoo]

btw is this is helpful you can see how we use serde_with to make it work in kimchi: https://github.com/o1-labs/proof-systems/blob/master/kimchi/src/proof.rs

[piotr-roslaniec]

@mimoo Thanks for chipping in. I played around with it a while back and I think this is going to be our preferred serialization method moving forward.

[piotr-roslaniec]

Closed by #67