generate test state from init/1' in jsx_to_term' and `jsx_to_json'

instead of doing it by hand

src/jsx_to_json.erl

@@ -298,7 +298,7 @@ handle_event_test_() ->
         {
             Title, ?_assertEqual(
                 JSON,
-                lists:foldl(fun handle_event/2, {start, [], #config{}}, Events ++ [end_json])
+                lists:foldl(fun handle_event/2, init([]), Events ++ [end_json])
             )
         } || {Title, JSON, _, Events} <- Data
     ].

src/jsx_to_term.erl

@@ -247,7 +247,7 @@ handle_event_test_() ->
         {
             Title, ?_assertEqual(
                 Term,
-                lists:foldl(fun handle_event/2, {[], #config{}}, Events ++ [end_json])
+                lists:foldl(fun handle_event/2, init([]), Events ++ [end_json])
             )
         } || {Title, _, Term, Events} <- Data
     ].