parking configuration should be migrated over to res_parking.conf

[lelutin]

With the current default configurations, asterisk gives the following warnings:

features_config.c:1533 unsupported_handler: Parkinglots are no longer configurable in features.conf; parking is now handled by res_parking.conf
features_config.c:1537 unsupported_handler: The option 'parkext' is no longer configurable in features.conf.
features_config.c:1537 unsupported_handler: The option 'parkpos' is no longer configurable in features.conf.
features_config.c:1537 unsupported_handler: The option 'context' is no longer configurable in features.conf.

So we should remove those from the default features in params.pp and make it possible to configure res_parking.conf instead.