Add a check gate at the PR level to validate that packages remains valid

[paraita]

There's no control over the packages changes and that leads to errors when injecting those packages into a Catalog. This is problematic for the ProActive release because it prevents the latter to boot properly.
A control check should be triggered on this repo at the PR step to validate that the packages integrity remains, either by putting in places some rules like a schema or simply run the loadPackages script on a mocked/blank Catalog.