The Ray Dashboard starts Serve in the `"_ray_internal_dashboard"` namespace. However, Serve by default starts in the `"serve"` namespace. This causes surprising behavior when working with the Serve CLI and REST API.
This change make the Ray Dashboard start Serve in the `"serve"` namespace, allowing the REST API to work intuitively with the Python API.
This change adds the GET, PUT, and DELETE commands for Serve’s REST API. The dashboard receives these commands and issues corresponding requests to the Serve controller.
