feat: Add user relation to black jack game entity

backend/src/main/java/de/szut/casino/blackjack/CardEntity.java

@@ -0,0 +1,15 @@
+package de.szut.casino.blackjack;
+
+
+import lombok.Getter;
+
+@Getter
+public class CardEntity {
+    private final Suit suit;
+    private final Rank rank;
+
+    public CardEntity(Suit suit, Rank rank) {
+        this.suit = suit;
+        this.rank = rank;
+    }
+}