Add optional timeout arguments to `cellular` and `gps` functions

[pulkin]

1. cellular.SMS.list
2. cellular.SMS.send
3. cellular.attach
4. cellular.activate cellular.gprs
5. gps.on

[pulkin]

6. cellular.flight_mode
7. cellular.register
8. cellular.stations

[pulkin]

1. Learn how variable number of arguments is implemented in docs: MP_DEFINE_CONST_FUN_OBJ_KW, etc;
2. Choose either of the above functions (fixing cellular.gprs is a bit more involved but still the same);
3. Change the corresponding MP_DEFINE_CONST_FUN_OBJ_0 into MP_DEFINE_CONST_FUN_OBJ_KW;

micropython/ports/gprs_a9/modcellular.c

Lines 495 to 525 in 0b89a2f

	STATIC mp_obj_t modcellular_sms_list(void) {
	// ========================================
	// Lists SMS messages.
	// Returns:
	// A list of SMS messages.
	// ========================================
	REQUIRES_NETWORK_REGISTRATION;
	SMS_Storage_Info_t storage;
	SMS_GetStorageInfo(&storage, SMS_STORAGE_SIM_CARD);
	sms_list_buffer = mp_obj_new_list(storage.used, NULL);
	sms_list_buffer_count = 0;
	SMS_ListMessageRequst(SMS_STATUS_ALL, SMS_STORAGE_SIM_CARD);
	WAIT_UNTIL(sms_list_buffer_count == storage.used, TIMEOUT_SMS_LIST, 100, mp_warning(NULL, "Failed to poll all SMS: the list may be incomplete"));
	mp_obj_list_t *result = sms_list_buffer;
	sms_list_buffer = NULL;
	uint16_t i;
	for (i = sms_list_buffer_count; i < result->len; i++) {
	result->items[i] = mp_const_none;
	}
	sms_list_buffer_count = 0;
	return (mp_obj_t)result;
	}
	STATIC MP_DEFINE_CONST_FUN_OBJ_0(modcellular_sms_list_obj, modcellular_sms_list);
	STATIC MP_DEFINE_CONST_STATICMETHOD_OBJ(modcellular_sms_list_static_class_obj, MP_ROM_PTR(&modcellular_sms_list_obj));

4. Change the function signature to

STATIC mp_obj_t fun(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
...
}

5. Parse arguments for a single / additional timeout argument;
6. Use the timeout argument WAIT_UNTIL macro or the wait loop (if any) instead of the corresponding constant (TIMEOUT_SMS_LIST in this particular case);

micropython/ports/gprs_a9/modcellular.c

Line 510 in 0b89a2f

WAIT_UNTIL(sms_list_buffer_count == storage.used, TIMEOUT_SMS_LIST, 100, mp_warning(NULL, "Failed to poll all SMS: the list may be incomplete"));

7. Note the constant default value and remove it from the corresponding header file

micropython/ports/gprs_a9/modcellular.h

Lines 66 to 73 in 0b89a2f

	#define TIMEOUT_SMS_LIST 10000
	#define TIMEOUT_SMS_SEND 10000
	#define TIMEOUT_GPRS_ATTACHMENT 15000
	#define TIMEOUT_GPRS_ACTIVATION 10000
	#define TIMEOUT_FLIGHT_MODE 10000
	#define TIMEOUT_LIST_OPERATORS 15000
	#define TIMEOUT_REG 10000
	#define TIMEOUT_STATIONS 2000

8. Build the firmware and test it;
9. PR here