add hash of public params for Nova & HyperNova (#118)

- implement hash of public params for Nova & HyperNova
- abstract pp_hash computation for folding schemes
- add pp_hash to solidity contract generator to verify the decider proof

folding-schemes/src/lib.rs

@@ -10,7 +10,7 @@ use thiserror::Error;
 
 use crate::frontend::FCircuit;
 
-pub mod ccs;
+pub mod arith;
 pub mod commitment;
 pub mod constants;
 pub mod folding;
@@ -122,7 +122,7 @@ where
     ) -> Result<(Self::ProverParam, Self::VerifierParam), Error>;
 
     fn init(
-        pp: &Self::ProverParam,
+        params: (Self::ProverParam, Self::VerifierParam),
         step_circuit: FC,
         z_0: Vec<C1::ScalarField>, // initial state
     ) -> Result<Self, Error>;