Drop enum class object hack

Place valueOf() and values() into the static scope of the corresponding enum
class

 #KT-5580 Fixed
 #KT-2410 Fixed

compiler/testData/diagnostics/tests/enum/starImportNestedClassAndEntries.kt

@@ -21,4 +21,4 @@ fun f1() = ENTRY
 fun f2() = ANOTHER
 fun f3() = Nested()
 fun f4() = Nested.foo()
-fun f5() = <!UNRESOLVED_REFERENCE!>values<!>()
+fun f5() = values()