OCPP v1.6/v2.0.1 deprecate dataclasses from calls and call results with the suffix 'Payload'

[Jared-Newell-Mobility]

Fixes #583

[OrangeTux]

I suggest to warn users using a DeprecationWarning. For example by doing something like this:

import warnings
from dataclasses import dataclass

@dataclass
class CancelReservation:
    reservation_id: int


@dataclass
class CancelReservationPayload(CancelReservation):
    def __post_init__(self):
        warnings.warn("CancelReservationPayload is deprecated, use CancelReservation instead.")

CancelReservation(reservation_id=3)
CancelReservationPayload(reservation_id=3)

Creating a CancelReservation() doesn't have any different effect. Whereas creating a CancelReservationPayload() prints a warning to stdout:

/tmp/deprecation.py:12: UserWarning: CancelReservationPayload is deprecated, use CancelReservation instead

Initializing a CancelReservation() doesn't have any affect. Creating a `CancelReservationPayload()