[flow][refactor] Remove internal apis of type_sig_utils

Summary:
The only usage can just be replaced by parse_and_pack_builtins.

Changelog: [internal]

Reviewed By: gkz

Differential Revision: D86830123

fbshipit-source-id: c6c5d2fef4eccbb91ddcd70a930e393333d0c199

Author: SamChou19815

src/parser_utils/exports/__tests__/exports_tests.ml

@@ -36,7 +36,7 @@ let parse_and_pack_module ~strict sig_opts contents =
 
 let parse_and_pack_builtins sig_opts contents =
   let (ast, _errors) = Parser_flow.program ~parse_options contents in
-  Type_sig_utils.(pack_builtins (parse_libs sig_opts [ast]))
+  Type_sig_utils.parse_and_pack_builtins sig_opts [ast]
 
 let make_test_formatter () =
   let open Format in

src/parser_utils/type_sig/type_sig_utils.mli

@@ -5,25 +5,6 @@
  * LICENSE file in the root directory of this source tree.
  *)
 
-val parse_libs :
-  Type_sig_options.t ->
-  (Loc.t, Loc.t) Flow_ast.Program.t list ->
-  Loc.t Type_sig_parse.tables
-  * ( Loc.t Type_sig_parse.binding_node SMap.t
-    * Loc.t Type_sig_parse.binding_node SMap.t
-    * (Loc.t Type_sig_parse.loc_node * Loc.t Type_sig_parse.exports) SMap.t
-    )
-
-val pack_builtins :
-  Loc.t Type_sig_parse.tables
-  * ( Loc.t Type_sig_parse.binding_node SMap.t
-    * Loc.t Type_sig_parse.binding_node SMap.t
-    * (Loc.t Type_sig_parse.loc_node * Loc.t Type_sig_parse.exports) SMap.t
-    ) ->
-  Type_sig_collections.Locs.index Type_sig.errno list
-  * Loc.t Type_sig_collections.Locs.t
-  * Type_sig_collections.Locs.index Packed_type_sig.Builtins.t
-
 val parse_and_pack_builtins :
   Type_sig_options.t ->
   (Loc.t, Loc.t) Flow_ast.Program.t list ->