Mostly finished implementation of the new deck? ALso added some tests

src/Nadeko.Econ/Deck/Regular/RegularCard.cs

@@ -0,0 +1,17 @@
+namespace Nadeko.Econ;
+
+public sealed class RegularCard : NewCard<RegularSuit, RegularValue>
+{
+    public RegularCard(RegularSuit suit, RegularValue value) : base(suit, value)
+    {
+    }
+
+    private bool Equals(RegularCard other)
+        => other.Suit == this.Suit && other.Value == this.Value;
+
+    public override bool Equals(object? obj)
+        => ReferenceEquals(this, obj) || obj is RegularCard other && Equals(other);
+
+    public override int GetHashCode()
+        => Suit.GetHashCode() * 17 + Value.GetHashCode();
+}