show local functions in structure view

#KT-13473 Fixed

idea/testData/structureView/fileStructure/LocalElements.after

@@ -0,0 +1,5 @@
+-LocalElements.kt
+ -foo(): Unit
+  bar(): Unit
+  -X
+   xyzzy(): Unit

idea/testData/structureView/fileStructure/LocalElements.kt

@@ -0,0 +1,8 @@
+fun foo() {
+    fun bar() { }
+
+    class X {
+        fun xyzzy() {
+        }
+    }
+}