Chat view should restore sessions with pending changes

[jrieken]

• have an agent session
• have changed files that aren't settled yet (not kept, nor undone)
• restart VS Code (install daily update)
• the chat view doesn't show the session

While I generally agree with the "fresh" chat view, I think this is a case where we should return to the last session

[bpasero]

I do not have strong feelings, but maybe @isidorn or @roblourens do.

With the introduction of the sessions in the chat view that also indicate pending changes to accept, I feel this is less of a problem because the reality will be that you will be having very many sessions to review with pending changes, the more sessions run in parallel.