An implementation of KT-7753: now enum constructors cannot be called explicitly.

Several tests are provided.
 #KT-7753 Fixed.

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

@@ -0,0 +1,13 @@
+// KT-7753: attempt to call enum constructor explicitly
+enum class A(val c: Int) {
+    ONE(1),
+    TWO(2),
+    THREE(3),
+    FOURTY_TWO();
+
+    var last: A? = null
+
+    constructor(): this(42) {
+        last = <!ENUM_CLASS_CONSTRUCTOR_CALL!>A(13)<!>
+    }
+}