Start working on making the state machine accessible via the api

src/main/java/com/monsieurmahjong/commonjong/api/MahjongGameOrchestrator.java

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+package com.monsieurmahjong.commonjong.api;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+
+import com.monsieurmahjong.commonjong.game.mahjong.MahjongGame;
+import com.monsieurmahjong.commonjong.rules.riichi.RiichiStandardRuleset;
+import com.monsieurmahjong.commonjong.rules.riichi.RiichiTileset;
+import com.monsieurmahjong.commonjong.rules.riichi.scoring.RiichiScoring;
+
+public class MahjongGameOrchestrator
+{
+    private static MahjongGameOrchestrator instance;
+    private Map<UUID, MahjongGame> ongoingMahjongGames;
+
+    private MahjongGameOrchestrator()
+    {
+        ongoingMahjongGames = new HashMap<>();
+    }
+
+    protected static MahjongGameOrchestrator getInstance()
+    {
+        if (instance == null)
+        {
+            instance = new MahjongGameOrchestrator();
+        }
+        return instance;
+    }
+
+    public static UUID createRiichiGame()
+    {
+        var mahjongGame = new MahjongGame(null, new RiichiStandardRuleset(new RiichiTileset(), new RiichiScoring()));
+        var orchestrator = getInstance();
+        var uuid = UUID.randomUUID();
+
+        orchestrator.ongoingMahjongGames.put(uuid, mahjongGame);
+
+        return uuid;
+    }
+
+    public static boolean hasMahjongGame(UUID uuid)
+    {
+        return getInstance().ongoingMahjongGames.get(uuid) != null;
+    }
+}

src/test/java/com/monsieurmahjong/commonjong/api/MahjongGameOrchestratorTest.java

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+package com.monsieurmahjong.commonjong.api;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.UUID;
+
+import org.junit.jupiter.api.Test;
+
+public class MahjongGameOrchestratorTest
+{
+    @Test
+    public void whenInvalidUUIDIsGiven_thenNoGameShouldBeFoundWithThisUUID()
+    {
+        var uuid = UUID.randomUUID();
+
+        var hasMahjongGame = MahjongGameOrchestrator.hasMahjongGame(uuid);
+
+        assertFalse(hasMahjongGame);
+    }
+
+    @Test
+    public void whenCreatingMahjongGame_thenThatGameShouldBeFoundInTheOrchestrator()
+    {
+        var uuid = MahjongGameOrchestrator.createRiichiGame();
+
+        var hasMahjongGame = MahjongGameOrchestrator.hasMahjongGame(uuid);
+
+        assertTrue(hasMahjongGame);
+    }
+}