Registrant API: add endpoint for requesting business registry information

[vohmar]

To enable registrant portal to display companies that were associated with the user while looking for the list of domains to return to user we need to add an option to request this information via registrant API.

Registrant API queries this information from business registry and saves this to cache table.

Registrant API should return to the portal comapny name, business registry number and country code

Karl's draft: