new: add storefront permissions api

[julia-rabello]

Types of changes

• New content (endpoints, descriptions or fields from scratch)
• Improvement (make an endpoint's title or description even better)
• Spelling and grammar accuracy (self-explanatory)

Changelog

Do not forget to update your changes to our Developer Portal's changelog. Did you create a release note?

• Yes, I already created a release note about this change.
• No, but I am going to.

[github-actions]

Thanks for your contribution. The .json file will be checked now with Spectral.