feat: add support for multiple event dates in variants

- Updated the FeaturedGroupService to include 'variants.eventDates' in the items query.
- Introduced a BelongsToMany relationship in EventDate for selected variants.
- Modified PurchaseItemResource and PurchaseItemSnapshotFactory to handle multiple event dates for variants.
- Enhanced StartCheckoutService to load event dates for variants.
- Updated TicketGeneratorService to accommodate event dates in ticket generation.
- Created migrations to support multi-value event dates and allow multiple variant values per attribute.
- Adjusted seeders to reflect new event date handling and added new attributes.
- Added tests to ensure correct functionality for multi-date variants and their integration with ticket generation.

app/Domains/Purchase/Services/Checkout/StartCheckoutService.php

@@ -278,6 +278,8 @@ class StartCheckoutService
             'variant.attachments',
             'variant.catalogItem',
             'variant.definitions.itemAttribute.attribute',
+            'variant.eventDates',
+            'variant.eventDate',
         ]);
     }