Add a workflow for deployments

[josecelano]

The first version can be triggered manually. In a second iteration, it can be triggered automatically when new docker images are available.

The idea is to do the same steps I do manually when deploying:

1. SSH into the server.

2. Execute the deployment script: ./bin/deploy-torrust-demo.com.sh.

3. Execute the smoke tests:

   cargo run --bin udp_tracker_client announce 144.126.245.19:6969 9c38422213e30bff212b30c360d26f9a02136422
   
   cargo run --bin http_tracker_client announce 144.126.245.19:6969 9c38422213e30bff212b30c360d26f9a02136422
   
   TORRUST_CHECKER_CONFIG='{
       "udp_trackers": ["144.126.245.19:6969"],
       "http_trackers": ["https://tracker.torrust-demo.com"],
       "health_checks": ["https://tracker.torrust-demo.com/api/health_check"]
   }' cargo run --bin tracker_checker

4. Check the logs of the tracker container to see if everything is working:

   ./share/bin/tracker-filtered-logs.sh