feat: ProductWithAttributes and ProductVariation interfaces added

[kidunot89]

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What does this implement/fix? Explain your changes.

• Two more interfaces added.
  • ProductWithAttributes
  • ProductVariation
• The ProductVariation object type has been replace with the SimpleProductVariation type.
• The other interfaces were renamed.
  • InventoriedProducts to InventoriedProduct
  • DownloadableProducts to DownloadableProduct
  • ProductsWithPricing to ProductWithPricing
  • ProductsWithDimensions to ProductWithDimensions
  • ProductsWithVariations to ProductWithVariations

Example

query {
  products(first: 100) {
    nodes {
      ... on ProductWithAttributes {
        defaultAttributes {
          nodes {
            label
            value
          }
        }
      }
      ... on ProductWithVariations {
        variations(first: 50) {
          nodes {
            name
            attributes {
              nodes {
                label
                value
              }
            }
          }
        }
      }
    }
  }
}

Does this close any currently open issues?

…

Any relevant logs, error output, GraphiQL screenshots, etc?

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Any other comments?

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Where has this been tested?

• WooGraphQL Version: …
• WPGraphQL Version: …
• WordPress Version:
• WooCommerce Version: