⚖️ Add opponent king buckets to passed pawns bucketed arrays

[eduherminio]

Test  | eval/passed-pawn-buckets-opposite-side
Elo   | 0.21 +- 1.69 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=32MB
LLR   | -2.26 (-2.25, 2.89) [0.00, 3.00]
Games | 75804: +21490 -21445 =32869
Penta | [2165, 9067, 15407, 9084, 2179]
https://openbench.lynx-chess.com/test/1200/

Test  | eval/passed-pawn-buckets-opposite-side
Elo   | 0.90 +- 15.06 (95%)
SPRT  | 40.0+0.40s Threads=1 Hash=128MB
LLR   | 0.06 (-2.25, 2.89) [-3.00, 1.00]
Games | 768: +200 -198 =370
Penta | [13, 94, 165, 102, 10]
https://openbench.lynx-chess.com/test/1209/

Passed tuned 10k #1355

After some merges:

Score of Lynx-eval-passed-pawn-buckets-opposite-side-5120-win-x64 vs Lynx 5107 - main: 22770 - 22226 - 39719  [0.503] 84715
...      Lynx-eval-passed-pawn-buckets-opposite-side-5120-win-x64 playing White: 17501 - 4993 - 19864  [0.648] 42358
...      Lynx-eval-passed-pawn-buckets-opposite-side-5120-win-x64 playing Black: 5269 - 17233 - 19855  [0.359] 42357
...      White vs Black: 34734 - 10262 - 39719  [0.644] 84715
Elo difference: 2.2 +/- 1.7, LOS: 99.5 %, DrawRatio: 46.9 %
SPRT: llr 2.9 (100.3%), lbound -2.25, ubound 2.89 - H1 was accepted