Add backgammon and board game crate (#5884)

* [ADD] backgammon, made pieces generic

* [ADD] board game crate

* [REMOVE] minor whitespace

* Fix BOM

* [CHANGE] feedback changes, condensed backgammon setup

* [CHANGE] swapped backgammon y positions to correct ones

Co-authored-by: fishfish458 <fishfish458>
Co-authored-by: Visne <39844191+Visne@users.noreply.github.com>

Content.Server/Tabletop/TabletopBackgammonSetup.cs

@@ -0,0 +1,71 @@
+using JetBrains.Annotations;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Serialization.Manager.Attributes;
+
+namespace Content.Server.Tabletop
+{
+    [UsedImplicitly]
+    public class TabletopBackgammonSetup : TabletopSetup
+    {
+        [DataField("boardPrototype")]
+        public string BackgammonBoardPrototype { get; } = "BackgammonBoardTabletop";
+
+        [DataField("whitePiecePrototype")]
+        public string WhitePiecePrototype { get; } = "WhiteTabletopPiece";
+
+        [DataField("blackPiecePrototype")]
+        public string BlackPiecePrototype { get; } = "BlackTabletopPiece";
+        public override void SetupTabletop(TabletopSession session, IEntityManager entityManager)
+        {
+            var board = entityManager.SpawnEntity(BackgammonBoardPrototype, session.Position);
+
+            const float borderLengthX = 7.35f; //BORDER
+            const float borderLengthY = 5.60f; //BORDER
+
+            const float boardDistanceX = 1.25f;
+            const float pieceDistanceY = 0.80f;
+
+            float getXPosition(float distanceFromSide, bool isLeftSide)
+            {
+                var pos = borderLengthX - (distanceFromSide * boardDistanceX);
+                return isLeftSide ? -pos : pos;
+            }
+
+            float getYPosition(float positionNumber, bool isTop)
+            {
+                var pos = borderLengthY - (pieceDistanceY * positionNumber);
+                return isTop ? pos : -pos;
+            }
+
+            void addPieces(
+                float distanceFromSide,
+                int numberOfPieces,
+                bool isBlackPiece,
+                bool isTop,
+                bool isLeftSide)
+            {
+                for (int i = 0; i < numberOfPieces; i++)
+                {
+                    session.Entities.Add(entityManager.SpawnEntity(isBlackPiece ? BlackPiecePrototype : WhitePiecePrototype, session.Position.Offset(getXPosition(distanceFromSide, isLeftSide), getYPosition(i, isTop))));
+                }
+            }
+
+            // Top left
+            addPieces(0, 5, true, true, true);
+            // top middle left
+            addPieces(4, 3, false, true, true);
+            // top middle right
+            addPieces(5, 5, false, true, false);
+            // top far right
+            addPieces(0, 2, true, true, false);
+            // bottom left
+            addPieces(0, 5, false, false, true);
+            // bottom middle left
+            addPieces(4, 3, true, false, true);
+            // bottom middle right
+            addPieces(5, 5, true, false, false);
+            // bottom far right
+            addPieces(0, 2, false, false, false);
+        }
+    }
+}