Add the process ID as a tag in Sentry exceptions

With the new Ponos authentication, we can set a custom tag to report the process ID within Sentry exceptions. This will make troubleshooting faster, since we no longer have to find which process caused the error, and this will allow us to continue to distinguish between errors inside or outside of processes. We used to be able to differentiate before, because the authenticated user was the internal user, but that's no longer the case.