feat: add chess board situation interface

chess/src/main/scala/io/github/chess/model/situations/Check.scala

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+package io.github.chess.model.situations
+import io.github.chess.model.ChessGameStatus
+
+/**
+ * The "check" situation in a chess game is when the king can be captured
+ * by the opponent in the next turn.
+ */
+class Check extends ChessBoardSituation:
+  override def checkOn(state: ChessGameStatus): Boolean = ???

chess/src/main/scala/io/github/chess/model/situations/CheckMate.scala

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+package io.github.chess.model.situations
+
+import io.github.chess.model.ChessGameStatus
+
+/**
+ * The "checkmate" situation in a chess game is when the king is always captured
+ * by the opponent in the next turn.
+ */
+class CheckMate extends ChessBoardSituation:
+  override def checkOn(state: ChessGameStatus): Boolean = ???

chess/src/main/scala/io/github/chess/model/situations/ChessBoardSituation.scala

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+package io.github.chess.model.situations
+
+import io.github.chess.model.ChessGameStatus
+
+/**
+ * Situation in a game of chess (i.e.: check, checkmate, stalemate...).
+ */
+trait ChessBoardSituation:
+  /**
+   * @param state the specified state of the game
+   * @return true if the game in the specified state is in this situation, false otherwise.
+   */
+  def checkOn(state: ChessGameStatus): Boolean

chess/src/main/scala/io/github/chess/model/situations/Stalemate.scala

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+package io.github.chess.model.situations
+
+import io.github.chess.model.{ChessBoard, ChessGameStatus}
+
+/**
+ * The "stalemate" situation is when the current player cannot move any
+ * pieces, but there's no checkmate.
+ */
+class Stalemate extends ChessBoardSituation:
+  override def checkOn(state: ChessGameStatus): Boolean = ???