[Feature] Support MultiModalityDet3DInferencer

[JingweiZhang12]

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Motivation

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Modification

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BC-breaking (Optional)

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Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
3. If the modification has potential influence on downstream projects, this PR should be tested with downstream projects.
4. The documentation has been modified accordingly, like docstring or example tutorials.

[codecov]

Codecov Report

Patch coverage: 43.26% and project coverage change: -0.03 ⚠️

Comparison is base (dfcf542) 47.27% compared to head (700548f) 47.24%.

❗ Current head 700548f differs from pull request most recent head 766c89f. Consider uploading reports for the commit 766c89f to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           dev-1.x    #2342      +/-   ##
===========================================
- Coverage    47.27%   47.24%   -0.03%     
===========================================
  Files          270      271       +1     
  Lines        22513    22648     +135     
  Branches      3513     3534      +21     
===========================================
+ Hits         10643    10701      +58     
- Misses       11193    11267      +74     
- Partials       677      680       +3     

Flag	Coverage Δ
unittests	47.24% <43.26%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmdet3d/apis/__init__.py	100.00% <ø> (ø)
mmdet3d/apis/inference.py	14.63% <0.00%> (-0.09%)	⬇️
mmdet3d/datasets/transforms/__init__.py	100.00% <ø> (ø)
mmdet3d/visualization/local_visualizer.py	33.78% <0.00%> (-0.23%)	⬇️
mmdet3d/datasets/transforms/loading.py	44.91% <25.58%> (-1.74%)	⬇️
...pis/inferencers/multi_modality_det3d_inferencer.py	52.27% <52.27%> (ø)
mmdet3d/apis/inferencers/lidar_det3d_inferencer.py	56.25% <75.00%> (ø)
mmdet3d/apis/inferencers/__init__.py	100.00% <100.00%> (ø)

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[Xiangxu-0103]

Just need to fix minor comments