Extraction Engine: When extracting to enum class body, place new declaration after the last entry

#KT-9629 Fixed

idea/testData/refactoring/extractFunction/basic/extractToEnumClassBody.kt

@@ -0,0 +1,10 @@
+// PARAM_DESCRIPTOR: value-parameter val n: kotlin.Int defined in E.A.foo
+// PARAM_TYPES: kotlin.Int
+enum class E {
+    // SIBLING:
+    A {
+        fun foo(n: Int) = <selection>n + 1</selection>
+    },
+    B,
+    C
+}