Report INVISIBLE_MEMBER on private class object usage

compiler/testData/diagnostics/tests/classObjects/invisibleClassObjects.kt

@@ -0,0 +1,48 @@
+//FILE:a.kt
+package a
+
+class A {
+    class object {
+        fun foo() {}
+    }
+}
+
+private class B {
+    class object {
+        fun bar() {}
+    }
+}
+
+class C {
+    private class object {
+        fun baz() {}
+    }
+}
+
+private class D {
+    private class object {
+        fun quux() {}
+    }
+}
+
+//FILE:b.kt
+package b
+
+import a.A
+import a.<!INVISIBLE_REFERENCE!>B<!>
+import a.C
+import a.<!INVISIBLE_REFERENCE!>D<!>
+
+fun test() {
+    f(A)
+    f(<!INVISIBLE_MEMBER!>B<!>)
+    f(<!INVISIBLE_MEMBER!>C<!>)
+    f(<!INVISIBLE_MEMBER!>D<!>)
+
+    A.foo()
+    <!INVISIBLE_MEMBER!>B<!>.<!INVISIBLE_MEMBER!>bar<!>()
+    <!INVISIBLE_MEMBER!>C<!>.<!INVISIBLE_MEMBER!>baz<!>()
+    <!INVISIBLE_MEMBER!>D<!>.<!INVISIBLE_MEMBER!>quux<!>()
+}
+
+fun f(<!UNUSED_PARAMETER!>unused<!>: Any) {}