Geo - Create Project Registries Endpoint in GraphQL

What/Why

Related to #219402 (closed)

Project Registries are still being served via Rails with no endpoint whatsoever. To convert to Vue and support via Self Service, we will need a way to fetch the data. As part of our efforts, this API should be built in GraphQL.

Proposal

Add Project Registries as a GraphQL endpoint, supporting all existing Rails functionality
Take into consideration #219402 (closed) when implementing