fix: separate type stub generation into a separate stage

At the moment because of the "needs:" machinery package jobs start at the same time as test jobs. That leads to overutilization of CI runners (example) because they are supposed to wait until unit testing is done.

Instead of using "needs:", here we separate "package" stage into "pre-package" and "package" and use dependencies: to tell where to download artifacts from. That way we have stages controling order of execution and dependencies: controlling artifacts dependencies instead of needs that mixes these two mechanisms.