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/classObjectInEnum.kt

@@ -0,0 +1,9 @@
+enum class E {
+    ENTRY
+
+    class object {
+        fun entry() = ENTRY
+    }
+}
+
+fun bar() = E.entry()

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

@@ -0,0 +1,10 @@
+enum class E {
+    ENTRY
+
+    private class object
+}
+
+fun foo() = E.values()
+fun bar() = E.valueOf("ENTRY")
+fun baz() = E.ENTRY
+fun quux() = <!INVISIBLE_MEMBER!>E<!>

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

@@ -1,9 +0,0 @@
-// FILE: 1.kt
-package a
-
-private enum class E { ENTRY }
-
-// FILE: 2.kt
-package b
-
-val e = a.<!INVISIBLE_MEMBER!>E<!>

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()