Deserialize public inputs

[MauroToscano]

A way to deserialize public inputs would be useful to load them outside the VM. This would be really useful for Rust provers.

For Cairo Platinum, we have created the issue here: lambdaclass/lambdaworks#727

We suggested two tasks:

• Add a deserializator for public inputs without layout params
• Add a deserialization for the full public inputs

To start with the first task a new Struct can be created PublicInputForDeserializer that contains the same fields but the params, and the derive can be done automatically by Serde. Then implement a to/from to convert it to the real PublicInput