Announce/publish AdGuardHome service via mDNS

### Prerequisites

Please answer the following questions for yourself before submitting an issue. **YOU MAY DELETE THE PREREQUISITES SECTION.**

- [x] I am running the latest version
- [x] I checked the documentation and found no answer
- [x] I checked to make sure that this issue has not already been filed

### Problem Description

The AdGuardHome API is pretty awesome, however, a service consuming that API has to ask the user for information. As it cannot find AdGuardHome on the network by itself (unless doing enumerating scan's and other guesses, which well... let's just not :wink:)

### Proposed Solution

It would be great if AdGuardHome published a zeroconf/mdns/dns-sd record, so an application that can consume the AdGuardHome API can auto-detect it on the network

### Alternatives Considered

None. Well, except maybe the AdGuard Home Hass.io add-on, it publishes this information inside it's Docker container startup towards Home Assistant (which consumes the API).

### Additional Information

- The impact and implementation time for this feature should be low.
- This would add the capability for every user of Home Assistant (including people not running the Hass.io system) to get a single click experience on integrating the two.
- It would be preferred to have a startup CLI argument to disable this feature.
- Example lib by Hasicorp:

```go
// Setup our service export
host, _ := os.Hostname()
info := []string{"AdGuard Home"},
service, _ := NewMDNSService(host, "_adguardhome._tcp", "", "", 3000, nil, info)

// Create the mDNS server, defer shutdown
server, _ := mdns.NewServer(&mdns.Config{Zone: service})
defer server.Shutdown()
```