Carbon support for time-zone-aware doctrine types

Hello,

Doctrine has two types, which handle time-zones: DateTimeTzImmutableType and DateTimeTzType. For carbon specifically, community has already written couple of types, which implement this:

https://github.com/beberlei/DoctrineExtensions/blob/master/src/Types/CarbonImmutableDateTimeTzType.php https://github.com/beberlei/DoctrineExtensions/blob/master/src/Types/CarbonDateTimeTzType.php

I would like to propose introduction of two doctrine types to handle time zones:

• carbontz
• carbontz_immutable