To fix pre-existing packaging and CI workflows

* Modify CMakeLists.txt to take into account ROS-2.

* Adaptation to ROS2

* Add a symlink to the RunCommand to call it RunPythonCommand and keep retro-compatibility.

* add some doc in the readme

* add missing files

* update the package.xml to reflect the ROS1/ROS2 optionnal build

* add ROS2 unit-test on the generation and use of the msg and services.

* add github action CI for this package. using the ros tools

* try to trigger github actions

* try to trigger the github action

* try to trigger the github action

* try to trigger the github action

* try to trigger the github action

* try to trigger the github action

* try to trigger the github action

* try to trigger the github action

* try to trigger the github action

* try to trigger the github action

* add ros1 unit-tests

* trigger github actions for this PR

* trigger github actions for this PR

* fix ros1 version in github actions

* fix CMakeLists.txt

* fix CMakeLists.txt

* fix ubuntu18.04 compatibility in tests

* fix constructor in ros1 unit test node

* fix ros1 unit-test on services

* fix ros1 unit-test on services

* fix ros1 unit-test on services

* remove ubuntu18.04 unit-test as it is too complexe to setup
Co-authored-by: Olivier Stasse <olivier.stasse@laas.fr>

Takes the services and messages from dynamic_graph_bridge to put them in this
package