Log not allowed workstation

### Prerequisites

- [X] I have checked the [Wiki](https://github.com/AdguardTeam/AdGuardHome/wiki) and [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions) and found no answer

- [X] I have searched other issues and found no duplicates

- [X] I want to request a feature or enhancement and not ask a question

### Description

I was playing with block/unblocing workstations, and I noticed that if workstation is not being served because its not in the allowed list, nothing tell you that on the logs (neither traffic log or anywhere)
Maybe add support for it ? "request from x.x.x.x blocked because not in allowed list"