Extract Class: Implement 'Extract Superclass' refactoring

#KT-11017 In Progress

idea/testData/refactoring/extractSuperclass/replaceSuperclass.kt.after

@@ -0,0 +1,15 @@
+// NAME: X
+interface T {}
+
+open class A
+
+open class X : A() {
+    // INFO: {checked: "true"}
+    fun foo() {
+
+    }
+}
+
+// SIBLING:
+class B : X(), T {
+}