Tracking of technical details of using shoutrrr

[favonia]

This is to track the technical details to implement #532 using shoutrrr.

• How to display all services in a RouterService (not all available services)?
• Should we set the title (or other params?)

PRs

• [x] Part 1: #633
• [x] Part 2: #640
• [ ] Part 2.5: Rework the message structure
• [ ] Part 3: Actually send notifications
• [ ] Part 4: Adjust message formats to match #641
• [ ] Part 5: Testing on real machines

Message

Current plan: These will be notified:

• [ ] Starting of the program unless it's one-time
• [ ] Configuration errors
• [ ] Use of deprecated settings (?)
• [x] IP detection error (every time!)
• [x] IP changes
• [ ] Successful detection of the same IP after failures (?)
• [ ] Failures to update DNS records
• [ ] Exiting of the program unless it's one-time

These will not be notified:

• [ ] Failure to ping monitors