Enabling and registering Suggested Reviewers

The design is here https://gitlab.com/gitlab-org/modelops/applied-ml/review-recommender/recommender-service/-/issues/10/designs/suggested-reviewers-settings.png , to be able to enable SR in Settings.

1. Frontend UI for project setting
2. Backend task to call the gRPC API to register the setting

• Registration API end point has been merged last thursday/friday. We need a client API to talk to that new endpoint including it's Ruby protobuf.
• We need a service to send there project info including generating a new token.
• Ruby protobuf definitions