Add Decider impl for Nova onchain (#66)

* Add Decider impl for Nova onchain

Add Decider impl for Nova onchain.
Update also the Decider trait.

Nova onchain decider: (compressed SNARK / final proof), in order to
later verify the Nova+CycleFold proofs onchain (in Ethereum’s EVM).

* PR review updates and few other changes

Cargo.toml

@@ -12,6 +12,7 @@ ark-crypto-primitives = { version = "^0.4.0", default-features = false, features
 ark-poly-commit = "^0.4.0"
 ark-relations = { version = "^0.4.0", default-features = false }
 ark-r1cs-std = { default-features = false } # use latest version from the patch
+ark-snark = { version = "^0.4.0"}
 ark-serialize = "^0.4.0"
 ark-circom = { git = "https://github.com/gakonst/ark-circom.git" }
 thiserror = "1.0"
@@ -26,6 +27,10 @@ espresso_subroutines = {git="https://github.com/EspressoSystems/hyperplonk", pac
 ark-pallas = {version="0.4.0", features=["r1cs"]}
 ark-vesta = {version="0.4.0", features=["r1cs"]}
 ark-bn254 = "0.4.0"
+ark-mnt4-298 = {version="0.4.0", features=["r1cs"]}
+ark-mnt6-298 = {version="0.4.0", features=["r1cs"]}
+ark-groth16 = { version = "^0.4.0" }
+rand = "0.8.5"
 tracing = { version = "0.1", default-features = false, features = [ "attributes" ] }
 tracing-subscriber = { version = "0.2" }
 
@@ -35,7 +40,10 @@ default = ["parallel"]
 parallel = [ 
     "ark-std/parallel", 
     "ark-ff/parallel",  
+    "ark-ec/parallel",  
     "ark-poly/parallel", 
+    "ark-crypto-primitives/parallel",  
+    "ark-r1cs-std/parallel",  
     ]
 
 # The following patch is to use a version of ark-r1cs-std compatible with