Use static annotation to optimize Bitboard Magic and Attacks

[lenguyenthanh]

Using @static annotation to compile all private val field as static field. The benchmark is staying the same or increasing so little probably because jit inlines those functions anyway. But lets do this to avoid any doubt.

here is the decompiled code before and after the change:
before:

public final class Attacks {
    public static long[] ATTACKS() {
        return Attacks$.MODULE$.ATTACKS();
    }

    public static long[][] BETWEEN() {
        return Attacks$.MODULE$.BETWEEN();
    }

    public static long[] BLACK_PAWN_ATTACKS() {
        return Attacks$.MODULE$.BLACK_PAWN_ATTACKS();
    }

    public static long[] FILES() {
        return Attacks$.MODULE$.FILES();
    }

    public static long[] KING_ATTACKS() {
        return Attacks$.MODULE$.KING_ATTACKS();
    }

    public static long[] KNIGHT_ATTACKS() {
        return Attacks$.MODULE$.KNIGHT_ATTACKS();
    }

    public static long[] RANKS() {
        return Attacks$.MODULE$.RANKS();
    }

    public static long[][] RAYS() {
        return Attacks$.MODULE$.RAYS();
    }

    public static long[] WHITE_PAWN_ATTACKS() {
        return Attacks$.MODULE$.WHITE_PAWN_ATTACKS();
    }
}

after

public final class Attacks {
    public static final long chess$bitboard$Attacks$$$all = -1L;
    public static final long[] RANKS = (long[])Array$.MODULE$.fill(8, Attacks$::chess$bitboard$Attacks$$_$$anonfun$1, ClassTag$.MODULE$.apply(Long.TYPE));
    public static final long[] FILES = (long[])Array$.MODULE$.fill(8, Attacks$::chess$bitboard$Attacks$$_$$anonfun$2, ClassTag$.MODULE$.apply(Long.TYPE));
    public static final long[][] BETWEEN = new long[64][64];
    public static final long[][] RAYS = new long[64][64];
    public static final long[] ATTACKS = (long[])Array$.MODULE$.fill(88772, Attacks$::chess$bitboard$Attacks$$_$$anonfun$3, ClassTag$.MODULE$.apply(Long.TYPE));
    public static final long[] KNIGHT_ATTACKS = (long[])Array$.MODULE$.fill(64, Attacks$::chess$bitboard$Attacks$$_$$anonfun$4, ClassTag$.MODULE$.apply(Long.TYPE));
    public static final long[] KING_ATTACKS = (long[])Array$.MODULE$.fill(64, Attacks$::chess$bitboard$Attacks$$_$$anonfun$5, ClassTag$.MODULE$.apply(Long.TYPE));
    public static final long[] WHITE_PAWN_ATTACKS = (long[])Array$.MODULE$.fill(64, Attacks$::chess$bitboard$Attacks$$_$$anonfun$6, ClassTag$.MODULE$.apply(Long.TYPE));
    public static final long[] BLACK_PAWN_ATTACKS = (long[])Array$.MODULE$.fill(64, Attacks$::chess$bitboard$Attacks$$_$$anonfun$7, ClassTag$.MODULE$.apply(Long.TYPE));
    public static final int[] chess$bitboard$Attacks$$$KNIGHT_DELTAS = new int[]{17, 15, 10, 6, -17, -15, -10, -6};
    public static final int[] chess$bitboard$Attacks$$$BISHOP_DELTAS = new int[]{7, -7, 9, -9};
    public static final int[] chess$bitboard$Attacks$$$ROOK_DELTAS = new int[]{1, -1, 8, -8};
    public static final int[] chess$bitboard$Attacks$$$KING_DELTAS = new int[]{1, 7, 8, 9, -1, -7, -8, -9};
    public static final int[] chess$bitboard$Attacks$$$WHITE_PAWN_DELTAS = new int[]{7, 9};
    public static final int[] chess$bitboard$Attacks$$$BLACK_PAWN_DELTAS = new int[]{-7, -9};
}