Earlier, we used to store the key data related to realm exports
in RealmAuditLog. This commit adds a separate table to store
those data.
It includes the code to migrate the concerned existing data in
RealmAuditLog to RealmExport.
Fixes part of #31201.
For exporting full with consent:
* Earlier, a message advertising users to react with thumbs up
was sent and later used to determine the users who consented.
* Now, we no longer need to send such a message. This commit
updates the logic to use `allow_private_data_export` user-setting
to determine users who consented.
Fixes part of #31201.
Prakhar Pratyush
Alex Vandiver
Anders Kaseorg