Change Signature: Support conversion between extension and non-extension functions

idea/testData/refactoring/changeSignature/ConvertReceiverToParameterWithNameClashBefore.kt

@@ -0,0 +1,7 @@
+val x1: Int
+
+class X(val x: Int)
+
+fun X.<caret>foo(x: Int): Boolean {
+    return this.x + x > x1
+}