code: func (h *Handler) getSiteNamespaces(w http.ResponseWriter, r *http.Request, _ httprouter.Params, c *SessionContext, site reversetunnel.RemoteSite) (interface{}, error) {
  	clt, err := site.GetClient()
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	namespaces, err := clt.GetNamespaces()
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	return getSiteNamespacesResponse{
  		Namespaces: namespaces,
  	}, nil
  }
docs: /* getSiteNamespaces returns a list of namespaces for a given site
  
  GET /v1/webapi/namespaces/:namespace/sites/:site/nodes
  
  Successful response:
  
  {"namespaces": [{..namespace resource...}]}
  */