Bug 1876574 - Add SameSite bit to partition-key origin attribute for first-party partitioning - r=timhuang

This patch is a no-op for observable functionality. All it does is add a bit to the partitionKey for OA, and then adds plumbing to be able to set it, and where it is required, sets it to false.
This is serialized identically to the absence of the bit, so nothing changes at all.

Differential Revision: https://phabricator.services.mozilla.com/D203155

netwerk/protocol/http/HttpBaseChannel.cpp

@@ -2423,7 +2423,6 @@ HttpBaseChannel::GetDocumentURI(nsIURI** aDocumentURI) {
 NS_IMETHODIMP
 HttpBaseChannel::SetDocumentURI(nsIURI* aDocumentURI) {
   ENSURE_CALLED_BEFORE_CONNECT();
-
   mDocumentURI = aDocumentURI;
   return NS_OK;
 }