Clear-Site-Data integration is incorrect

[annevk]

I was made aware of https://datatracker.ietf.org/doc/html/draft-cutler-httpbis-partitioned-cookies#name-partitioned-cookies-and-cle (is there a more recent document?) which seems quite wrong.

In particular the discussion in privacycg/storage-partitioning#11 ended up with the conclusion that Clear-Site-Data should not have the ability to clear beyond the partition of the site that emits it, which is not what this document is doing.

It also has rather undefined "top-document" terms that somehow support a same-site comparison. All of that ought to be cleaned up too.

[aselya]

We would like to add a new section defining an algorithm for computing a response's cookie partition key, which would could also be the definition used for a corresponding request's key.

This new algorithm will address the creation of a new partitioned cookie when Set-Cookie contains Partitioned and provides a method for calculating the partition key needed for Clear-Site-Data.