Add ros2 compatibility on ros2 branch

[dmiklic]

Use the appropriate branch of the p2os repo (ros2 or ros2_port)

[juricapapak]

During the process of building the ariac_environment package on ros2 crystal I'm getting the following error:

CMake Error at CMakeLists.txt:7 (find_package):
  By not providing "Findcatkin.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "catkin", but
  CMake did not find one.

  Could not find a package configuration file provided by "catkin" with any
  of the following names:

    catkinConfig.cmake
    catkin-config.cmake

  Add the installation prefix of "catkin" to CMAKE_PREFIX_PATH or set
  "catkin_DIR" to a directory containing one of the above files.  If "catkin"
  provides a separate development package or SDK, be sure it has been
  installed.

I've successfully installed all the dependencies using rosdep and have catkin installed, just not through ros2. I don't see any ros2 branches on the official repo. I've had similar issues before but I've always been able to find the appropriate .cmake config file. Not this time, presumably because it's not a ros2 package.

[dmiklic]

Yes, ROS2 does not use Catkin any more. So instead of Catkin (build system) and catkin_make (build tool), it uses ament as the build system and colcon as the build tool. Please check the Migration guide for more details.

[dmiklic]

Also, check out this and this for some Gazebo specifics in ROS2.

[dmiklic]

However, looking at the status of the p2os port we might have to start thinking of a backup plan, maybe using ros2 bridge.