Fix false positive "Unused symbol" for type alias & private nested class/object

#KT-21526 Fixed
 #KT-30527 Fixed

idea/testData/inspectionsLocal/unusedSymbol/innerClass.kt

@@ -0,0 +1,19 @@
+// PROBLEM: none
+
+import MVE.Used.Companion.doStuff1
+
+fun main() {
+    MVE("").test()
+}
+
+data class MVE(private val parameter: CharSequence) {
+    fun test() = parameter.doStuff1()
+
+    private data class Used<caret>(val parameter: CharSequence) {
+        companion object {
+            fun CharSequence.doStuff1() = Used(this).doStuff2()
+        }
+
+        private fun doStuff2() = ""
+    }
+}