Proposal: add interactive mode for pixi upgrade

[baka-gourd]

like https://pnpm.io/cli/update#--interactive--i

Currently, upgrades can either be performed in their entirety or limited to specific features or packages. Given the increasingly rapid pace of vulnerability fixes and version updates these days, it might be worth adding a more user-friendly option that allows users to choose what to upgrade. After all, you don’t know what will be upgraded until you check. The only similar option available right now is dry-run; this would be a significant quality-of-life improvement.