Add world assets for lunarsim (#38).

[mazm0002]

Related to space-ros/demos#50.
This PR adds assets for the lunar world, which are pulled into the lunarsim demo.

[mkhansenbot]

Looks good to me

[ivanperez-keera]

@mkhansenbot @EzraBrooks This PR leaves files in Github LFS. I've never used that. How do we want to manage that? Do we need to set anything up on our end? Do we need to copy files over so that we don't lose them if the original requester removes the files?

[ivanperez-keera]

@mazm0002 I need to make some changes to this PR to merge the work. Can you please also give my user permission to make changes to the simulation repo under element-robotics?

[mazm0002]

@ivanperez-keera I've given you permissions, let me know if there's any issues

[ivanperez-keera]

Update (2025/09/04): Check if PNG images should also be stored in LFS. All files should be in LFS.

We need to update the documentation to tell people that they won't get the actual files unless they have LFS enabled.

[ivanperez-keera]

Checked that all images are stored in LFS.