Add key to assets and Add an asset at a specific position

Assets can now be identified by a user-defined key that is unique only within the asset's container (a product variant or a category). Before only the id of the assets could be used to identify them. Assets can now be placed at a specific position within the asset list when adding them to a ProductVariant or a Category.

• [API] Assets have a new optional key field that can be set during creation of the asset or afterwards by the new update action SetAssetKey on products and on categories endpoints.

• [API] An Asset key can now be used as an alternative identifier to the asset ID on following update actions:

  • on ProductVariant:
    • RemoveAsset
    • SetAssetTags
    • ChangeAssetName
    • SetAssetDescription
    • SetAssetSources
    • SetAssetCustomType
    • SetAssetCustomField
  • on Category:
    • RemoveAsset
    • SetAssetTags
    • ChangeAssetName
    • SetAssetDescription
    • SetAssetSources
    • SetAssetCustomType
    • SetAssetCustomField

• [API] Added optional field position on update actions:

  • AddAsset to product variants
  • AddAsset to categories