pixi global should report after each environment instead after the whole operation

[Hofer-Julian]

pixi global sync collects changes and only reports them at the end. It does that so that it can filter some of them. For example, there's no need to mention that you added a package if you afterward remove the whole environment.

However, at the moment, with pixi global sync we only report at the very end. By reporting after each environment is handled, we give earlier feedback while still removing redundant info.