[FIR] Report ABSTRACT_MEMBER_NOT_IMPLEMENTED_BY_ENUM_ENTRY on enum entries with initializer

#KT-59577 Fixed

compiler/testData/diagnostics/tests/enum/enumEntryInAbstractEnum.fir.kt

@@ -0,0 +1,13 @@
+enum class EnumClass {
+    E1 {
+        override fun foo() = 1
+        override val bar: String = "a"
+    },
+
+    <!ABSTRACT_MEMBER_NOT_IMPLEMENTED_BY_ENUM_ENTRY!>E2<!> {
+
+    };
+
+    abstract fun foo(): Int
+    abstract val bar: String
+}