WIP: feat: add Atlas description

[lvjonok]

This PR adds an Atlas description. I attempted to follow contribution guidelines, in README.md you can find notes on the process of converting URDF to MuJoCo.

What help I am needed:

• licence: I have used URDF from drake project. So, probably the licence should be copied from there, but I am unaware.
• textures: I have found another URDF description of Atlas which also contained textures and .dae files. My attempt was to use drake textures and add them to .xml using mapping (which .obj should use which textures) from .dae files. I have added an example of textures loading to utorso mesh because it will be more convenient to try for others.

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[kevinzakka]

Regarding the license, it looks like it's a 3-clause BSD license so we can accept it. You can just copy paste that license verbatim.

[lvjonok]

Hello! When I could expect any further feedback or suggestions regarding textures mapping?

[yuvaltassa]

Hi, can you please clarify the issue with the textures?
I find the item in the OP regarding this issue quite unclear.

[lvjonok]

Hi, can you please clarify the issue with the textures? I find the item in the OP regarding this issue quite unclear.

In the original repository there are .DAE files with textures. I took as example utorso body and tried to apply textures I have found in .dae file.

1. The first question I have is can I add two textures to one body? In the corresponding .dae file I see that it loads two .jpg files.
2. The next question is how to actually understand parameters for the material component based on .dae file. Do I have to add some external parameters based on original mesh file?

That is why I have added the scene textures.xml which one can load and check that textures are loaded correctly.