Top-Level Storage Access: Mozilla proposal

[tomcrane]

This proposal would allow Authorization Flow for third party cookies to continue in its current form, if adopted by Chrome even if general support for third party cookies is removed:

https://github.com/bvandersloot-mozilla/top-level-storage-access

Our engagement so far with this issue is here:
privacycg/storage-access#72 (comment)

and:
bvandersloot-mozilla/top-level-storage-access#2

Next step - find out how best to declare institutional support.