Link Sniffer improvements and better internal error reporting.

This update improves Link Sniffer. In the previous version, website scan results were shown in technical jargon without any information about what the user could do to take precautions. In this version, Link Sniffer uses clearer language about the websites it analyzes such as — it looks safe, it's probably fine, be careful, or looks risky. Users can click the "What should I do?" button and find guidance on what precautions to take at each level of risk.
No other features were changed. No new permissions were requested. No data collection was added.