Add STL mesh support

[Wumpf]

What

Allows to log stl through Asset3D or load it directly into the viewer via drag/drop or the CLI

Screen.Recording.2024-02-20.at.23.10.32.mov

To test that the api works I ran
python ./docs/code-examples/all/asset3d_simple.py ../buckle.stl with this file.

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using newly built examples: app.rerun.io
  • Using examples from latest main build: app.rerun.io
  • Using full set of examples from nightly build: app.rerun.io
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG
• If applicable, add a new check to the release checklist!

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