Generated safe routes

[Atulin]

Inspired by https://github.com/daviddotcs/safe-routing

Currently, to get a route to a given endpoint, we must rely either on magic strings, or the endpoint must be given a name for use with link generator or redirect response.

The routes, at least, could be source-generated, and perhaps available as a static property of the handler. For example, GetAllBooks.Route.

As a step above that, and a step towards the safe-routing way, a whole redirect result object could be created, so that return TypedResults.Redirect(nameof(GetAllBooks)) or similar can be replaced with return GetAllBooks.Redirect or some such.