Copy: Support class copying

#KT-8180 Fixed
 #KT-9054 Fixed

idea/testData/refactoring/copy/copyClassToExistingFile/after/bar/A.kt

@@ -0,0 +1,12 @@
+package bar
+
+import foo.B
+
+fun foo() {
+
+}
+
+class A {
+    val a: A = A()
+    val b: B = B()
+}

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

@@ -0,0 +1,11 @@
+package foo
+
+class A {
+    val a: A = A()
+    val b: B = B()
+}
+
+class B {
+    val a: A = A()
+    val b: B = B()
+}