feat: Add 'upgrade' subcommand to very_good packages, if possible with --recursive flag

[mnkeis]

Description Having a project with multiple flutter / dart packages nested under a root directory. It would be helpful to be able to run very_good packages upgrade --recursive whenever we have to upgrade the dependencies of all our packages.

Steps To Reproduce Currently, we have to manually dive into every package directory and manually run flutter packages upgrade on each of them.

Expected Behavior Whenever we want to upgrade our packages dependencies, just run very_good packages upgrade --recursive from the root directory of our project to upgrade all the dependencies on all packages directory / directories, even if there isn't a pubspec.yaml on the root directory.

Additional Context This functionality should run similarly as very_good packages get --recursive, unfortunately there's the complexity of packages dependencies and dependencies constraints that often makes the upgrade process not as smooth as we would like. Maybe the process could be interactive for cases when it is necessary to take manual decisions