[strands_movebase] Add option to use head_camera as well

This adds the parameter `with_head_camera:=<bool>` to `movebase.launch`. If enabled, it will make the obstacle voxel grid higher to account for the head camera and listen to points on topic `/move_base/head_points_clearing` as published by `backtrack.launch` in `backtrack_behaviour` package. If you want to use the `backtrack_behaviour` recovery behaviour, you have to set `with_head_camera:=true` when launching `movebase.launch`.

This also fixes private namespace parameters for all the nodes in this package since that is needed when using multiple nodes of the same type.