frontend: track and notify of known safety issues

[ES-Alexander]

Current behaviour

Cockpit doesn't know about ArduPilot User Alerts, so known safety issues in firmwares could get missed unnecessarily. Similarly, there are no mechanisms for this in general (e.g. if a Cockpit safety issue is discovered, it should be possible to notify users of this without needing to first update to a new version).

Expected or desired behaviour

1. When internet access is available, update known issues from the ArduPilot User Alerts database, and any similar databases provided by us and/or by the user
   • This could be enabled by allowing the user to specify a list of URLs to pull from, similar to BlueOS's multiple extension manifests
2. If a known problematic configuration, firmware version, Cockpit version, and/or installed widget add-on is detected, inform the user about the issue and recommended mitigation steps

Prerequisites

• I have checked to make sure that a similar request has not already been filed or fixed.