Share entity base classes between CIL and source extraction

csharp/extractor/Semmle.Extraction.CIL/Entities/Base/Tuple.cs

@@ -0,0 +1,22 @@
+namespace Semmle.Extraction.CIL
+{
+    /// <summary>
+    /// A tuple that is an extraction product.
+    /// </summary>
+    internal class Tuple : IExtractionProduct
+    {
+        private readonly Extraction.Tuple tuple;
+
+        public Tuple(string name, params object[] args)
+        {
+            tuple = new Extraction.Tuple(name, args);
+        }
+
+        public void Extract(Context cx)
+        {
+            cx.Cx.Emit(tuple);
+        }
+
+        public override string ToString() => tuple.ToString();
+    }
+}