Visualizing gaussian splats

[billamiable]

Type

• Bug fix (non-breaking change which fixes an issue): Fixes #
• New feature (non-breaking change which adds functionality). Resolves #
• Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

This PR, along with two other PRs (#7192, #7193), will fix #7154

Checklist:

• I have run python util/check_style.py --apply to apply Open3D code style
  to my code.
• This PR changes Open3D behavior or adds new functionality.
  • Both C++ (Doxygen) and Python (Sphinx / Google style) documentation is
    updated accordingly.
  • I have added or updated C++ and / or Python unit tests OR included test
    results (e.g. screenshots or numbers) here.
• I will follow up and update the code if CI fails.
• For fork PRs, I have selected Allow edits from maintainers.

Description

[update-docs]

Thanks for submitting this pull request! The maintainers of this repository would appreciate if you could update the CHANGELOG.md based on your changes.

[benjaminum]

Thanks for the PR! Please have a look at the comments

[ssheorey]

Hi @billamiable we don't support sh degree > 2 for rendering, but we do support it for other operations (reading and writing 3DGS files, and in the future editing 3DGS data). I would skip this warning here, and instead only add it if the user tries to display a 3DGS point cloud with 3 or higher degree.