Exposed visibility checking, a set of exposed visibility tests, some test fixes

Effective visibility mechanism introduced.
Local is considered as public, java protected as Kotlin protected, java package private as Kotlin private.

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

@@ -10,6 +10,6 @@ class A {
     }
 }
 
-fun f1() = A.Companion.B.<!INVISIBLE_MEMBER!>C<!>
+fun <!EXPOSED_FUNCTION_RETURN_TYPE!>f1<!>() = A.Companion.B.<!INVISIBLE_MEMBER!>C<!>
 
 fun f2() = A.Companion.B.C.<!INVISIBLE_MEMBER!>foo<!>()