Port/hypernova multifolding (#10)

* Port HyperNova's multifolding from https://github.com/privacy-scaling-explorations/multifolding-poc adapting and refactoring some of its methods and structs.

Note: adapted mle.rs methods from dense to sparse repr.

Co-authored-by: George Kadianakis <desnacked@riseup.net>

* HyperNova: move CCS struct outside of LCCCS & CCCS

HyperNova nimfs: move CCS structure outside of LCCCS & CCCS, to avoid
carrying around the whole CCS and duplicating data when is not needed.

Also add feature flags for the folding schemes.

---------

Co-authored-by: George Kadianakis <desnacked@riseup.net>

src/folding/circuits/cyclefold.rs

@@ -28,7 +28,7 @@ impl<C: CurveGroup, GC: CurveVar<C, CF<C>>> ECRLC<C, GC> {
 }
 
 #[cfg(test)]
-mod test {
+mod tests {
     use super::*;
     use ark_ff::{BigInteger, PrimeField};
     use ark_pallas::{constraints::GVar, Fq, Fr, Projective};