Import as its Own Endpoint

There may be some small advantage to offering an `/import` endpoint when someone explicitly intends to use it instead of having to `/update`. This would require it's own RESTful checks and responses.

An `/import` is a perfect mix of `/create` and `/update`. It "updates an item in the graph" by "creating a new root" in RERUM which references the origin URI through __rerum.history.previous.

I think this endpoint would be a POST request which responds 201 on success. Currently, it is behind PUT `/update` and responds 200 upon success. Something to think about if we decide to do this.

Comienza comparando el comportamiento existente de los endpoints /create y PUT /update. Determina las comprobaciones y respuestas REST necesarias para un POST /import que cree una nueva raíz que haga referencia a la URI de origen mediante __rerum.history.previous. La tarea se considera completada cuando el comportamiento del endpoint, incluida una respuesta 201 exitosa, está definido e implementado de forma coherente.

Escrito por el modelo de indexación a partir del texto del issue.