Add packages added with rosdistro_additional_recipes.yaml to "Available Packages" tables

[traversaro]

Thanks to the rosdistro_additional_recipes.yaml support, we are adding more packages to the robostack distribution that are not released in rosdistro/bloom upstream. However, these packages are not listed in the available packages list in https://robostack.github.io/ . Ideally, we should list them, possibly on a different table to avoid confusion with packages actually released upstream.

The code to change is in:

• https://github.com/RoboStack/robostack.github.io/blob/master/utils/compare_pkg_completeness.py
• https://github.com/RoboStack/robostack.github.io/blob/master/.github/workflows/update-package-table.yml

and I guess this is a good task for anyone interested in starting contributing to robostack.