Use IdTagInfo datatype instead of Dict for id_tag_info occurances (#278)

The `Authorize.conf` message in the v1.6 spec defines what fields should
be present for an `IdTagInfo`. The dataclass for this already exists in
`datatypes.py`, as of the recently merged #250 PR.

This PR makes use of it by importing the dataclass, and using it instead
of the more losely typed `typing.Dict`.

ocpp/v16/call_result.py

@@ -1,6 +1,7 @@
 from dataclasses import dataclass
 from typing import Dict, List, Optional
 
+from ocpp.v16.datatypes import IdTagInfo
 from ocpp.v16.enums import (
     AvailabilityStatus,
     CancelReservationStatus,
@@ -46,7 +47,7 @@
 
 @dataclass
 class AuthorizePayload:
-    id_tag_info: Dict
+    id_tag_info: IdTagInfo
 
 
 @dataclass
@@ -94,7 +95,7 @@ class MeterValuesPayload:
 @dataclass
 class StartTransactionPayload:
     transaction_id: int
-    id_tag_info: Dict
+    id_tag_info: IdTagInfo
 
 
 @dataclass
@@ -104,7 +105,7 @@ class StatusNotificationPayload:
 
 @dataclass
 class StopTransactionPayload:
-    id_tag_info: Optional[Dict] = None
+    id_tag_info: Optional[IdTagInfo] = None
 
 
 # The CALLRESULT messages that flow from Charge Point to Central System are