Only private constructors for sealed / enum classes #KT-12377 Fixed

Also #KT-8497 Fixed

idea/testData/inspections/redundantVisibilityModifier/redundantVisibilityModifier.kt

@@ -20,3 +20,13 @@ class E : D() {
     public override fun willBecomePublic() {
     }
 }
+
+enum class F private constructor(val x: Int) {
+    FIRST(42)
+}
+
+sealed class G constructor(val y: Int) {
+    private constructor(): this(42)
+
+    object H : G()
+}