Route request via project

See https://docs.gitlab.com/ee/architecture/blueprints/cells/routing-service.html for background

1. Assume the Cell publish route rules that allows to classify the requests.
2. Assume the Cell has classify API
3. The routing service will use the project path to obtain the sharding key. This sharding key is sent to a random Cell to classify. The classify API will return the cell to route. See https://docs.gitlab.com/ee/architecture/blueprints/cells/routing-service.html#router-configured-to-perform-dynamic-routing-based-on-classification