feat: make gates serializable

src/gates/comparison.rs

@@ -28,7 +28,7 @@ use plonky2::plonk::vars::{
 use plonky2::util::bits_u64;
 
 /// A gate for checking that one value is less than or equal to another.
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Default)]
 pub struct ComparisonGate<F: Field64 + Extendable<D>, const D: usize> {
     pub(crate) num_bits: usize,
     pub(crate) num_chunks: usize,
@@ -414,8 +414,8 @@ impl, const D: usize> PackedEvaluableBase
     }
 }
 
-#[derive(Clone, Debug)]
-struct ComparisonGenerator<F: RichField + Extendable<D>, const D: usize> {
+#[derive(Clone, Debug, Default)]
+pub struct ComparisonGenerator<F: RichField + Extendable<D>, const D: usize> {
     row: usize,
     gate: ComparisonGate<F, D>,
 }