aar should log authorization errors

[Samuel Allan]

If we have a scenario where everything is set up between a client ams in push mode and the aar, but the client certificate is not added to aar with --publisher permission, we see the following:

- from the client: "ams.ams ... Registry: Failed to push new updates to registry: 401 Unauthorized"
- from aar: no logs

It would be good to log authorization errors, especially in the case where a client is trusted but tries to push when it isn't allowed to push. It would help find the cause of the issue faster in the above scenario.