Display Last Seen Server Visible IP/Agent Public IP on Fleet Agent Status

**Describe the enhancement:**
Display a Column on the Fleet Agents page and the Dashboard which lists the Public IP / IP which the fleet server receives logs from for each agent entry. Optionally, support details such as X-Forwarded-For headers if the Fleet server is behind a WAF.

**Describe a specific use case for the enhancement or feature:**
This will help in correlating traffic flows to the fleet server with active/authorized agents.