Add new option for building headless open3d

[saratpoluri]

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

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.

[timohl]

If python/requirements_viz.txt defines the visualization requirements, dash should probably be removed from python/requirements.txt, right?

Open3D/python/requirements.txt

Lines 1 to 6 in 1868f43

	numpy>=1.18.0
	dash>=2.6.0
	werkzeug>=3.0.0
	flask>=3.0.0
	nbformat>=5.7.0
	configargparse

Also, it might be good to add a try block to these imports with a nice error message:

Open3D/python/open3d/visualization/draw_plotly.py

Lines 12 to 14 in 1868f43

	from dash import html
	from dash import dcc
	from dash import Dash

Also, I am not sure if this becomes a problem when dash is removed from requirements.
This imports the plotly functions:

Open3D/python/open3d/visualization/__init__.py

Lines 19 to 21 in 1868f43

	from .draw_plotly import get_plotly_fig
	from .draw_plotly import draw_plotly
	from .draw_plotly import draw_plotly_server

And this imports it in the main open3d __init__.py:

Open3D/python/open3d/__init__.py

Line 127 in 1868f43

import open3d.visualization

I would suspect it will cause a missing import error.