feat: Do a breaking change release

[eseidel]

• Make –staging the default`
• Make –flutter-version explicit/required
• Remove “confirm” prompt for release and patch (in release it's completely silly, and patch is only preventing shiping to live by default, which can be fixed by default track)
• Make –release-version required (to prevent us building twice)
• Require patch signing (This isn’t breaking. We’d just move to using shorebird default keys.)

[felangel]

There's also https://github.com/shorebirdtech/shorebird/issues/1382 which is our second most upvoted issue.