Create update and delete item attributes

Item attributes allow you to define specific characteristics for items. Common examples of attributes include size, color, and material. Well-defined attributes are important because they enable item discovery and make catalog management easier.
This endpoint creates and updates item attributes to be assigned later.
Note:
1) You can add and manage unlimited attributes for your items. Once they are created, they appear as a selectable option on product pages.
2) In addition, you can assign attributes to items on an individual level or in bulk.