Modify create event endpoint to accept a list of DrinkActions

[Tschonti]

When the user creates an event, they should have the option to add the drinkActions to that event. So a CreateDrinkActionDto[] (except there is no need for the eventId field on the drinkAction dto. find a nice way of removing that field) field should be on the CreateEventDto. The list can be empty, but use classvalidator to validate the nested object.
Modify the create method of event service to create both the event and the drinkactions (prisma docs)

There's no need to modify the update endpoint, the POST/PATCH/DELETE endpoints of the DrinkAction controller can be used to modify the drinkActions of an event once it's created.

depends on #10