Extract Function: Take duplicates into account when choosing placement of extracted function

#KT-5916 Fixed

idea/testData/refactoring/extractFunction/duplicates/insertBeforeDuplicates.kt.after

@@ -0,0 +1,8 @@
+fun foo() {
+    fun i(): Int {
+        return 1 + 1
+    }
+
+    val x = i()
+    val y = i()
+}