[nav2] nav2_gazebo_spawner does not support specifying yaw
the gazebo spawner supports specifying the x,y,z position. However, there is not way to provide roll, pitch, yaw when spawning a robot.
This seems like a simple enough thing to do. If it's not enabled for some reason, can someone help explain the reason? If it's not enabled because nobody added it, I would be happy to make those changes and submit a pull request.