Following the approach we did for keeping requests at the same location, these changes introduce
new location for responses. `SuggestedRoutesResponse` is moved there and renamed to
`RouterSuggestedRoutes` and code is updated accordingly.
New type `Route` defined (since a single route is composed of zero or more paths).
Types `Route`, `Path`, `Graph` and `Node` belong to a new `routs` package now.