Add automatic fsck task on package install/uninstall

Before and after calling a package install or uninstall, it would be useful to call an fsck task which will check, report and fix the registry.
Also add an mp-fsck command to nuxeoctl.

Fixing bugs like NXP-19081 is good but it's worth to check the registry before and after any change. Such a feature would have permitted to identify NXP-19081 before publishing the 6.0-HF03 which broke the registry on nuxeo-core-redis key because of wrong overlapping use of copy and update tasks, exposing a trap in the code later revealed by the 6.0-HF27 uninstall.