Backup DHCP leases like PiHole

### 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

#### What problem are you trying to solve?
Now the leases are somehow encrypted into leases.db. Cannot read IP and hostname and don't know if a backup will function

#### Proposed solution
Save DHCP leases in yaml file