Migrate packaging_features module to Drupal 9

In order to migrate www.eclipse.org/downloads/packages to Drupal 9, we will need to migrate the https://gitlab.eclipse.org/eclipsefdn/it/websites/drupal/packaging_features module.

This module should live within our eclipsefdn d9 module under the name eclipsefdn_packages. The packaging_features is also the home of the eclipse_installer module. I am fine with consolidating these 2 modules under packaging_features.

I am willing to discuss this if someone prefers we split this into 2 modules.

The eclipse installer migration is scheduled for Q3: #23 (closed)