Utilize const generics

[Jan-Frase]

Heavily inspired by what chessbit does pretty much everywhere. (Which itself was learned this technique from Gigantua)

For example:
https://github.com/thuijbregts/chessbit/blob/boardstate_stats/chessbit/MoveGenerator.h

    template <bool side>
    ForceInline U64 pawnsAtkForward(U64 pM) {
        if constexpr (side == white) return pM >> 8;
        return pM << 8;
    }

Removes the if at runtime!
This entire functions gets compiled down to a rightshift for white and leftshift for black and nothing else (maybe a few moves).

In rust we can do the same by writing something like this:

#[inline(always)]
pub const fn pawns_atk_forward<const SIDE: bool>(pawn_mask: u64) -> u64 {
    if SIDE {
        pawn_mask >> 8  // White
    } else {
        pawn_mask << 8  // Black
    }
}

Applying this pattern all over the code base should result in incredible performance gains.