[Feature] Add pipelines for BEVDet

[HuangJunJie2017]

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Motivation

Update the transformation in mmdet3d to support requirements in the multi-camera 3D object detection

Modification

1. Support multi-view wrapper to wrap the transformation designed for single-view situation into multi-view situation.
2. Support random rotation and return the rotation angle.
3. Support random crops with a limited range and return the cropping ROI.

BC-breaking (Optional)

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Use cases (Optional)

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Checklist

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

[CLAassistant]

All committers have signed the CLA.

[Tai-Wang]

Just need to fix minor comments. Others LGTM

[codecov]

Codecov Report

Merging #1580 (dfc19fe) into master (bb20469) will increase coverage by 0.09%.
The diff coverage is 74.68%.

@@            Coverage Diff             @@
##           master    #1580      +/-   ##
==========================================
+ Coverage   50.16%   50.26%   +0.09%     
==========================================
  Files         223      223              
  Lines       19104    19182      +78     
  Branches     3134     3153      +19     
==========================================
+ Hits         9584     9642      +58     
- Misses       8940     8959      +19     
- Partials      580      581       +1     

Flag	Coverage Δ
unittests	50.26% <74.68%> (+0.09%)	⬆️

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

Impacted Files	Coverage Δ
mmdet3d/datasets/__init__.py	100.00% <ø> (ø)
mmdet3d/datasets/pipelines/__init__.py	100.00% <ø> (ø)
mmdet3d/datasets/pipelines/transforms_3d.py	86.08% <74.68%> (-1.32%)	⬇️
mmdet3d/datasets/pipelines/test_time_aug.py	51.04% <0.00%> (ø)

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