Fix workspace such that docker-ros-generated images can be used as base images for docker-ros

[lukaszanger]

The following modifications are necessary to enable the usage of docker-ros-generated images, which already have their install space and their src folder, as base images for docker-ros:

• Create new bash script .install-dependencies.sh for a newly started pipeline run instead of appending an existing one.
• If the install space already exists in the scope of the base image (docker-ros-generated), move this install space in order to make space for a new one.
• Remove potentially existing src folder which might exist in the scope for the base image (docker-ros-generated).
• Source from both, from the moved install space coming from the base image (docker-ros-generated) and from the newly created install space.

[lreiher]

Upgrade version after CI has succeeded, then merge