Bridge between PFCSes and R1CSes.
PFCSes are a generalization of R1CSes.
Thus, there is an embedding of R1CSes into PFCSes,
which we reify by providing a mapping from R1CSes and PFCSes.
- Translate a list of R1CS constraints to a list of PFCS constraints.
- Translate an R1CS (sparse) vector to a PFCS expression.
- Translate an R1CS vector element to a PFCS expression.
- Translate an R1CS to a PFCS.
- Translate an R1CS constraint to a PFCS constraint.