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.