Parse '@' annotations on enum entries

Just drop truncating builder's creation as we parse only escaped annotations
and will not `eat` entry identifier

compiler/testData/psi/annotation/at/enumEntries.kt

@@ -0,0 +1,13 @@
+enum class A {
+    [Ann] @Ann(1) X : A()
+
+    @Ann Y : A() {}
+
+    private @Ann() Z : A()
+
+    @Ann @private Q
+
+    Ann() W
+
+    @Ann fun foo() {}
+}