Make TypeConstructor.isFinal return false for enums

The reason is that before dc02b2e3ab and 8a0dcca957,
TypeConstructor.isFinal for some class descriptors
(DeserializedClassDescriptor, LazyJavaClassDescriptor,
MutableClassDescriptor) were implemented as `isFinalClass` (which is
`modality == FINAL && kind != ENUM_CLASS`), and all others as
`modality == FINAL` or simply true/false. This led to differences in
behavior depending on the exact instance of the class descriptor.
Now that TypeConstructor.isFinal is always `modality == FINAL`, some
tests (PseudoValueTestGenerated) fail because the finality of some type
constructors changed and these tests render final vs non-final type
constructors differently.

In this commit, TypeConstructor.isFinal is now made to behave safer,
i.e. considering enum class type constructor to be non-final (as was the
case earlier for some ClassDescriptor instances). Some diagnostics might
disappear (e.g. FINAL_UPPER_BOUND) but it doesn't look like a big deal

compiler/testData/cfg/declarations/classesAndObjects/ObjectEnumQualifiers.values

@@ -10,10 +10,10 @@ enum class E(val x: Int) {
     E1(0)
 }
 ---------------------
-      <v0>: Int   NEW: magic[FAKE_INITIALIZER](val x: Int) -> <v0>
-      <v1>: E     NEW: magic[FAKE_INITIALIZER](E1(0)) -> <v1>
-0     <v2>: Int   NEW: r(0) -> <v2>
-(0)   <v3>: *     NEW: call((0), <init>|<v2>) -> <v3>
+      <v0>: Int      NEW: magic[FAKE_INITIALIZER](val x: Int) -> <v0>
+      <v1>: {<: E}   NEW: magic[FAKE_INITIALIZER](E1(0)) -> <v1>
+0     <v2>: Int      NEW: r(0) -> <v2>
+(0)   <v3>: *        NEW: call((0), <init>|<v2>) -> <v3>
 =====================
 == C ==
 class C {
@@ -26,7 +26,7 @@ class C {
 == foo ==
 fun foo() = E1.x + O.y + C.z
 ---------------------
-E1                 <v0>: E             NEW: r(E1) -> <v0>
+E1                 <v0>: {<: E}        NEW: r(E1) -> <v0>
 x                  <v1>: Int           NEW: r(x|<v0>) -> <v1>
 E1.x               <v1>: Int           COPY
 O                  <v2>: O             NEW: r(O) -> <v2>