Light class codegen: all objects are considered static

Simplify code handling access flag computation
Fix a problem where kotlin nested object wasn't producing a nested light class

compiler/testData/asJava/lightClasses/NestedObjects.kt

@@ -0,0 +1,15 @@
+// A
+
+class A {
+    class B {
+        object I
+
+        object II
+    }
+
+    object C {
+        object D {
+            object G
+        }
+    }
+}