feat: prime field specializations

[lonerapier]

use nightly specialisation feature to make field methods default so that it can be overridden

impl<const P: usize> const Add for PrimeField<P> {
  default type Output = Self;

  default fn add(self, rhs: Self) -> Self { Self { value: (self.value + rhs.value) % Self::ORDER } }
}

and then overridden by BinaryField

pub type BinaryField = PrimeField<2>;

impl Add for BinaryField {
  type Output = Self;

  #[allow(clippy::suspicious_arithmetic_impl)]
  fn add(self, rhs: Self) -> Self::Output { BinaryField::new(self.value ^ rhs.value) }
}

[lonerapier]

not needed due to #126