`support/ark_ff_06`: Implement the `BigInteger` trait.

[github-actions]

On 2026-05-08 @prestwich wrote in e17160d “Merge pull request #584 from Robert-MacWha/main”:

Implement the BigInteger trait.

    PrimeField,
    biginteger::BigInt,
    fields::models::{Fp, FpConfig},
};

// FEATURE: Implement the `BigInteger` trait.

// BigInt

impl<const BITS: usize, const LIMBS: usize> From<BigInt<LIMBS>> for Uint<BITS, LIMBS> {
    fn from(value: BigInt<LIMBS>) -> Self {

From src/support/ark_ff_06.rs:12