Rework inbound federation to accept requests optimistically. The HTTP Signatures Plug will not attempt to fetch the actor or key and will fail early.
If the signature cannot be validated we pass the required data into the Oban job with a reduced priority and increase the timeout to 20 seconds. The Oban job will handle the actor and key fetching before attempting to validate the activity again. This job will be retried 5 times by default.
Another welcome side effect is that actors who change their keys can federate to Pleroma instances immediately instead of needing to wait the default value of 86400s / 24 hours before the key will be fetched again.
This will prevent a user with a large number of posts from negatively affecting performance of the outgoing federation queue if they delete their account.
This fixes a race condition bug where keys could be regenerated
post-federation, causing activities and HTTP signatures from an user to
be dropped due to key differences.
