[FEATURE] Repeat buyer attribute available via Receipts

[mozunk]

Is your feature request related to a problem? Please describe. I'm always frustrated when I cannot thank my repeat buyers because that attribute is only available when fulfilling orders via Etsy.com and not via the API.

Describe the solution you'd like Add previous_purchases attribute to receipt APIs where previous_purchases attribute is the number of transactions the buyer has had with the seller previously.

Describe alternatives you've considered Add is_repeat_buyer boolean attribute to receipt APIs if count of prior transactions is too expensive to vend.

[benjymouse]

+1 Great idea. Our clients would really appreciate this.