Add "Find Usages" tests for nested/inner classes and objects

idea/testData/findUsages/kotlin/findObjectUsages/kotlinNestedObjectUsages.0.kt

@@ -0,0 +1,8 @@
+// PSI_ELEMENT: org.jetbrains.jet.lang.psi.JetObjectDeclarationName
+package a
+
+class A {
+    object <caret>O {
+        var foo: String = "foo"
+    }
+}