{base,}sdk: Add Docker support

By default Docker stores the Docker images in /var/lib/docker/ which is located in the root partition, which run out of space very fast when downloading Docker images.
The same occurs with Flatpak.

Back in the long past we had to have separate partitions due to how the application framework worked. This is no more requested and the system can use a single partition.

Add docker package, and add user to docker group so Apertis SDK user can use Docker out-of-box.

Signed-off-by: Frédéric Danis frederic.danis@collabora.com