Consider merging IP and port for clear explanation

https://github.com/AdguardTeam/dnsproxy/blob/f35ca3e650ab099795cb457b360d080af8125a24/config.yaml.dist#L12-L15

Current YAML have this:
```
listen-addrs:
- "0.0.0.0"
listen-ports:
- 53
```

and this is unclear - what will happen if I replace to:
```
listen-addrs:
- "127.0.0.1"
- "192.168.34.56"
listen-ports:
- 53
- 5353
```

will it open:
- 127.0.0.1:53
- 127.0.0.1:5353
- 192.168.34.56:53
- 192.168.34.56:5353

To avoid such confusion, why not merge IP and port like this:

```
server-listen:
- "127.0.0.1:53"
- "192.168.34.56:5353"
```