Copy: Support top-level declarations

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

@@ -0,0 +1,9 @@
+package bar
+
+import foo.B
+
+val a: Int get() {
+    a
+    val b: B = B()
+    return 0
+}

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

@@ -0,0 +1,12 @@
+package foo
+
+val a: Int get() {
+    a
+    val b: B = B()
+    return 0
+}
+
+class B {
+    val a: A = A()
+    val b: B = B()
+}