Do not report redeclaration when outer class and default object's members clash

Previously we prohibited classes and properties with the same name (now it's unnecessary)
Add test for backends that they support qualified (by default object name) member references inside class body

compiler/testData/codegen/box/classes/defaultObjectSameNamesAsInOuter.kt

@@ -0,0 +1,18 @@
+class A {
+    private val p: Int
+        get() = 4
+
+    default object B {
+        val p: Int
+            get() = 6
+    }
+
+    fun a() = p + B.p
+}
+
+
+fun box(): String {
+    if (A().a() != 10) return "Fail"
+
+    return "OK"
+}