Fix header scope for secondary constructors

Add companion object's scope and nested classes

 #KT-6996 fixed

compiler/testData/codegen/box/secondaryConstructors/accessToCompanion.kt

@@ -0,0 +1,21 @@
+class A(val result: Int) {
+    companion object {
+        fun foo(): Int = 1
+        val prop = 2
+        val C = 3
+    }
+    object B {
+        fun bar(): Int = 4
+        val prop = 5
+    }
+    object C {
+    }
+
+    constructor() : this(foo() + prop + B.bar() + B.prop + C) {}
+}
+
+fun box(): String {
+    val result = A().result
+    if (result != 15) return "fail: $result"
+    return "OK"
+}