Add prompts to `coder start` to update the workspace

[bpmct]

For developers who primarily connect from their desktops (SSH and IDE plugins), there's no great way to update their workspaces. While #6049 will contribute towards this, we can also add prompts when a user manually starts if they want to update their workspace.

[github-actions]

This issue is becoming stale. In order to keep the tracker readable and actionable, I'm going close to this issue in 7 days if there isn't more activity.