Extract Function: Implement duplicate search

idea/testData/refactoring/extractFunction/duplicates/defaultCF.kt

@@ -0,0 +1,20 @@
+// PARAM_TYPES: kotlin.Int
+// PARAM_TYPES: kotlin.Int
+// PARAM_DESCRIPTOR: value-parameter val a: kotlin.Int defined in foo
+// PARAM_DESCRIPTOR: value-parameter val b: kotlin.Int defined in foo
+
+// SIBLING:
+fun foo(a: Int, b: Int) {
+    <selection>println("a = $a")
+    println("b = $b")
+    println(a + b*a)</selection>
+}
+
+fun bar() {
+    val x = 1
+    val y = 2
+
+    println("a = $x")
+    println("b = $y")
+    println(x + y*x)
+}