Add RealSense post-processing filters to RSBagReader

[aekanman]

Add RealSense post-processing filters to RSBagReader

Type

• Bug fix (non-breaking change which fixes an issue): Fixes #
• New feature (non-breaking change which adds functionality). Resolves o3d.t.io.RSBagReader() with libRealSense Depth Post-Processing #6164
• Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

This adds libRealSense depth post-processing support to o3d.t.io.RSBagReader() playback.

RealSense bag playback already reads and aligns depth/color frames, but users could not apply the standard libRealSense depth filters during bag reading. This PR adds an ordered Python filters argument to RSBagReader.open() so depth post-processing can be configured before depth is aligned to color. This resolves #6164 by adding libRealSense depth post-processing support to o3d.t.io.RSBagReader() playback.

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

Changes:

• Adds RSBagReader::Open(filename, filters) for ordered RealSense depth post-processing filters.
• Adds Python overload:
  reader.open(filename, {"decimation": {"filter_magnitude": 2}}).
• Supports decimation, spatial, temporal, and hole_filling.
• Supports common libRealSense options:
  filter_magnitude, filter_smooth_alpha, filter_smooth_delta, and holes_fill.
• Applies filters before aligning depth to the color frame.
• Validates unsupported filters/options before playback thread startup.
• Preserves filter configuration across EOF seek restart.
• Adds tutorial docs, changelog entry, and a software-only Python test using SampleL515Bag.

Test results:

PATH=/opt/anaconda3/lib/python3.12/site-packages/clang_format/data/bin:$PATH python util/check_style.py --no_parallel
# All files passed style check

git diff --check
# passed

python -m pytest python/test/t/io/test_realsense.py::test_RSBagReader_post_processing_filters -q
# 1 xpassed

python -m pytest python/test/t/io/test_realsense.py::test_RSBagReader -q
# 1 xfailed, matching the existing RealSense bag-reader test marker