add more test baselines around enum constraints

add more test baselines around enum constraints

Summary:
I'm just adding some more baseline tests. Some of them reveal bugs in the direct-decl-parser.

They are all to embody my hard-earned knowledge, which I documented in shallow_decl_defs.ml:
```
type shallow_class_const = {
  scc_abstract: bool;
  scc_name: Typing_defs.pos_id;
  scc_type: decl_ty;
      (** This field is used for two different meanings in two different places...
      enum class A:arraykey {int X="a";} -- here X.scc_type=\HH\MemberOf<A,int>
      enum B:int as arraykey {X="a"; Y=1; Z=B::X;} -- here X.scc_type=string, Y.scc_type=int, Z.scc_type=TAny
      In the later case, the scc_type is just a simple syntactic attempt to retrieve the type from the initializer. *)
  scc_refs: Typing_defs.class_const_ref list;
      (** This is a list of all scope-resolution operators "A::B" that are mentioned in the const initializer,
      for members of regular-enums and enum-class-enums to detect circularity of initializers.
      We don't yet have a similar mechanism for top-level const initializers. *)
}
```

Differential Revision: D27807165

fbshipit-source-id: 98cbfd6564c2df4ba24b501a24040ce67867e199