Marketplace: Create endpoint for adding database mapping for vendor

[gavande1]

Details

When vendors are onboarded we need to create their mapping in database tables in order to onboard them correctly. We will create an endpoint (that we will later use through WC.com) that accepts a vendor name and wpcom_user_id and:

• adds a store_vendor with a given name
• adds store_vendor_wpcom_user for the given wpcom_user_id

We can reuse the authentication mechanism used for updating webhook urls, but as first pass we will use is_proxied + is_automattian check so that we can trigger it manually.

[gavande1]

This task has already been completed. I am closing it now.

[gavande1]

My bad, this is about adding a new endpoint.