Docker Service deployment (Stack)

I'd like to see support for running, updating and managing AdGuardHome via docker and more specifically a Docker Swarm set-up using `docker stack deploy` (//Docker Swarm mode is far far far simpler to use and operationalize than k8s!//).

Somewhat related is #448

I'm happy to contribute to this but it would also require #377 to be resolved with up-to-date upstream images built in some kind of CI. Ideally using Docker Hub's own Automated Build would be nice. #514 would help a lot with this.

A (//not yet tested//) `adguardhome.yml` (//Docker Stackfile//): would look like this:

```#!yaml
version: "3.4"

services:
adguardhome:
image: adguardteam/adguardhome:latest
ports:
- "53:53/udp"
networks:
- bridge
volumes:
- adguardhomedata:/data
deploy:
replicas: 1

networks:
bridge:
external: true

volumes:
adguardhomedata:
driver: local
```