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/diagnostics/tests/enum/compareTwoDifferentEnums.kt

@@ -0,0 +1,16 @@
+// FILE: JavaEnumA.java
+
+public enum JavaEnumA {}
+
+// FILE: JavaEnumB.java
+
+public enum JavaEnumB {}
+
+// FILE: test.kt
+
+enum class KotlinEnumA
+enum class KotlinEnumB
+
+fun jj(a: JavaEnumA, b: JavaEnumB) = a == b
+fun jk(a: JavaEnumA, b: KotlinEnumB) = a == b
+fun kk(a: KotlinEnumA, b: KotlinEnumB) = a == b