AgentHost: Better experience for out of date agent hosts

[roblourens]

Today we show a notification message that is not clear, and the user is blocked from connecting to the agent host. We should tune the message and offer a button to force-kill and update the agent host.

[roblourens]

• Local AH: n/a
• SSH to remote: a button for us to run code agent kill and reconnect
• Tunnel to remote: suggest to the user to run code agent kill and reconnect