Ability to change hostname only in DHCP static leases

### 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

### The problem

I can not change only hostname of clients in DHCP static lease without the need to enter IP address.

### Proposed solution

An ability to change only hostname of clients in DHCP static lease without the need to enter IP address is needed so the clients can still have dynamic IP.

### Alternatives considered and additional information

_No response_