message: Make FieldHelpers work with Field instead of FftField
diff: -use ark_ff::FftField;
  +use ark_ff::Field;
  /// Field element helpers
  -pub trait FieldHelpers<F: FftField> {
  +pub trait FieldHelpers<F: Field> {
  /// Deserialize from bytes
  fn from_bytes(bytes: &[u8]) -> Result<F, &str>;
  @@ -21,7 +21,7 @@ pub trait FieldHelpers<F: FftField> {
  fn to_bits(self) -> Vec<bool>;
  }
  -impl<F: FftField> FieldHelpers<F> for F {
  +impl<F: Field> FieldHelpers<F> for F {
  fn from_bytes(bytes: &[u8]) -> Result<F, &str> {
  F::deserialize(&mut &*bytes).map_err(|_| "Failed to deserialize field bytes")
  }
  