Auto "add package" when listing manager actions, when appropriate

### What does it do ?

Automatically calls `addPackage` when listing manager actions (`?a=system/logs`) if an action is prefixed with a namespace.

### Why is it needed ?

Unless the third party package registers itself (extension_packages), when listing manager actions dealing with third party tables, packages and loaded, thus we can't get appropriate objects (filling the logs with loads of `Could not load class: ClassName from mysql.classname. className::load() is not a valid static method.`).

### To do before merge

- [ ] make sure most (all ?) third party packages follow the file structure convention (`namespace/model/`)