Create subclass intention implemented #KT-8473 Fixed

Can be used for implementing interfaces / abstract classes / sealed classes or extending open classes

idea/testData/quickfix/implement/inProtectedCompanion.kt.after

@@ -0,0 +1,10 @@
+// "Create subclass" "true"
+// SHOULD_BE_AVAILABLE_AFTER_EXECUTION
+
+class Container {
+    protected companion object {
+        open class Base
+    }
+
+    protected class BaseImpl : Companion.Base()
+}