Remove the action from the URI for the resource to allow individual
referencing and collections of nested resources.

The current API namespace is shared across all the callers so responses
will be filtered by visibility of the caller or denied in the absence of
authorization to use the passed input parameters.

Implement a paginator over the list of sessions visible to a caller.
The paginator is opportunistic as it will return an upper bounded set
using the client hint, and opaque as it will make no commitments on the
content of the pagination token.

The creation of sessions allows to submit a set of them to treat them as
an aggregate when requesting to operate on a certain peering posture.
This commit adds a field to the input and output series such that the
client can univocally identify which sessions have been processed
successfully or not without relying on implicit ordering of the input or
result set.

Implement a method to depeer by deleting existing sessions. The
batched creation method does not create an obvious collection resource
on the server side that may be used for a depeering situation therefore
this commit only implements individual session deletion.

To tackle a situation where depeering is desired for a whole metro or
IX while respecting this RESTful interface, we will need to define a
separate aggregate resource that can be used to operate atomically on
the set of target sessions.

This commit adds the soft deleted semantics described in the original
spec where a set of sessions is requested for deletion and the response
will include a status in the deletion of the request.

This commit also recreates these semantics in the individual session
deletion.

As per the different discussions, this commit removes references to
identifiers used to identify parts of an inflight request that
disambiguate failure scenarios. They may be addressed later.

It also removes the partial successful reponse conveyed through a
redirect error code. The rationale to use only the 200 success code
is that the response for a batched request has been successfully
processed and the response may still contain references to items which
were not successful. Clients will have to introspect the response to
decide what to do with those failed items.