Fix Kotlin definitions search for classes which can only be used in a local search scope (KT-13753)

idea/testData/search/definitions/testNestedClass.kt

@@ -0,0 +1,8 @@
+// CLASS: Outer.Base
+// SEARCH: class:Derived
+
+class Outer {
+    private abstract class Base
+
+    private class Derived : Base()
+}