Add PXE Support to the DHCP Server

### 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

PXE boot is a very useful feature but requires an expensive managed switch.

### Proposed solution

Adding PXE support to the DHCP server of Adguard Home would be a valuable feature. This way I would see an advantage to use the DHCP server in Adguard and not in my home router, that despite being an expensive model, supporting mesh and wifi6, does not have PXE support.

### Alternatives considered and additional information

I believe that's a simple feature which would bring a lot of value to the user.