[C#] Override ToString to give name of PrimitiveType.

Author: mjpt777

csharp/sbe-dll/PrimitiveType.cs

@@ -207,5 +207,7 @@ public SbePrimitiveType Type
  {
  get { return _sbePrimitiveType; }
  }
+
+ public override string ToString() => PrimitiveName;
  }
 }