Want updated status in Copilot status bar if background agent requires input

[bamurtaugh]

Ref https://github.com/microsoft/vscode-internalbacklog/issues/6527

• Kick off a background agent
• The agent requires input
• I expected its info in the Copilot status bar (both in the message and the icon) to reflect the need for input

I know we've discussed a variety of ways to draw user attention more closely when an agent requires input, but I thought we might not have an issue discussing this option, so opening here.

[bpasero]

I have a feeling we will eventually get rid of the entry in the status bar in favour of something in the title bar where it makes more sense to have sessions. The status should be reserved more for things that happen in the editor area.

[bamurtaugh]

I think this issue is quite similar to https://github.com/microsoft/vscode-internalbacklog/issues/6206. Both issues are about getting notified more when agents complete, they just focus slightly differently on cloud vs background, and where the notification should happen. Should we close one of these in favor of the other?