first batch of REST to GraphQL conversions for products and variants

[tekhaus]

Shopify will fully deprecate the REST product and variant endpoints as of Feb 1, 2025. To prepare for that deprecation, many of the tasks in the library will need to be converted to use GraphQL in lieu of those endpoints.

Broadly, any usage of the following REST object calls will need to be converted:

- shop.products
- shop.variants
- collection.products
- inventory_item.variant
- inventory_level.variant
- line_item.product
- line_item.variant
- product.collections
- product.images *️
- product.metafields
- product.variants *️
- variant.inventory_item
- variant.inventory_levels
- variant.metafields
- variant.product

Additional REST conversions may make sense along the way.

• See https://learn.mechanic.dev/resources/tutorials/converting-tasks-from-shopify-rest-to-graphql for more details

This batch includes some of the more popular tasks as well as a variety of usage that can be referenced for additional conversions.

[tekhaus]

TODO: change this to "contains" on next batch to support product create