Copy: Support top-level declarations

idea/testData/refactoring/copy/copyLocalFunction/after/bar/a.kt

@@ -0,0 +1,8 @@
+package bar
+
+fun a() {
+    fun b() {
+
+    }
+    b()
+}

idea/testData/refactoring/copy/copyLocalFunction/after/foo/test.kt

@@ -0,0 +1,8 @@
+package foo
+
+fun a() {
+    fun b() {
+
+    }
+    b()
+}