Use custom joint configuration when spawning robot inside Ignition Gazebo

[AndrejOrsula]

In the default joint configuration that the robot is spawned in ([0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]), the robot has one of the joints outside of its position limits and there is a self-collision of hand with one of the lower links.

I do not know any good way to spawn model into Ignition Gazebo with a specific non-default configuration. It can be done programatically though (via joint position reset).

For now, I increased the MoveIt 2 joint position tolerances and disabled collision geometry for arm in the examples.