Variant metafields not accessible via product.variants

[lousaint]

Description

Variant metafields are not included in the variant data accessible via product.variants or product.getVariants().

From what I can see, variant metafields are successfully synced from Shopify and stored in the shopify_data table, but Product::getVariants() only gets the ProductVariant record from the shopify_data table, which does not include the variant metafield data. These are stored in separate Metafield records, and would need to be retrieved and added to each variant.

Steps to reproduce

1. For a product where the variants have metafields defined, access the product's variants via product.getVariants().
2. The variant arrays contain no metafields element.

Additional info

• Craft version: 5.8.17
• PHP version: 8.2.20
• Database driver & version: MySQL 8.0.36
• Plugins & versions:
  CKEditor 4.10.1
  Cloudflare 3.1.0
  DigitalOcean Spaces Filesystem 3.2.0
  Feed Me 6.10.1
  Guest Entries 4.0.1
  oEmbed 3.1.5
  Postmark 3.1.0
  Retour 5.0.12
  SEO 5.0.0
  Shopify 6.0.5
  Shortcodes 4.0.1
  Smith 3.1.1
  Social Login 2.0.10
  Typesense 5.8.0
  Vite 5.0.1

[linear]

PT-2949