Add :array-type option to json-parse-string

Add :array-type option to json-parse-string

* src/json.c (enum json_array_type): New type.
(struct json_configuration): New field array_type.
(json_parse_args): Rename the last argument.  Handle the
:array-type keyword argument (bug#32793).
(Fjson_parse_string): Update the docstring accordingly.
(json_to_lisp): Handle the case of :array-type being `list'.  Add
a call to 'rarely_quit' inside the loop.
(syms_of_json): Define new symbols.
(Fjson_serialize, Fjson_insert, Fjson_parse_string)
(Fjson_parse_buffer): Update the config struct initializers.