Derive Macro SmallFpConfig 

#[derive(SmallFpConfig)]
{
    // Attributes available to this derive:
    #[modulus]
    #[generator]
}

Derive the SmallFpConfig trait for small prime fields.

The attributes available to this macro are:

• modulus: Specify the prime modulus underlying this prime field.
• generator: Specify the generator of the multiplicative subgroup.

Note: Only Montgomery backend is supported.