[Improvement] Remove dependency package warnings

[congee524]

This PR removes dependency package warnings using import_module_error_xxx hooks

[innerlee]

Looks good. Have you tested on your machine?

[congee524]

Import all modules of mmaction and there are no warnings or errors.
Train a recognizer and there's no problem.
Train a detector, it will raise an error 'ValueError: FastRCNN is not registered in LOCALIZERS, RECOGNIZERS or DETECTORS'. This is consistent with the previous performance

Directly import a function or a class in mmdet, and the error will be raised correctly, such as "ImportError: Please install mmdet to use MaxIoUAssignerAVA."

[congee524]

I forgot to test it with mmdet installed. Plz wait for minutes.

[codecov]

Codecov Report

Merging #583 (ad671e2) into master (5c1093e) will decrease coverage by 0.02%.
The diff coverage is 56.75%.

@@            Coverage Diff             @@
##           master     #583      +/-   ##
==========================================
- Coverage   84.13%   84.10%   -0.03%     
==========================================
  Files         121      122       +1     
  Lines        8617     8633      +16     
  Branches     1431     1435       +4     
==========================================
+ Hits         7250     7261      +11     
- Misses       1015     1018       +3     
- Partials      352      354       +2     

Flag	Coverage Δ
unittests	84.09% <56.75%> (-0.03%)	⬇️

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

Impacted Files	Coverage Δ
mmaction/models/backbones/resnet3d.py	90.61% <ø> (+0.21%)	⬆️
mmaction/models/backbones/resnet3d_slowfast.py	84.61% <ø> (+0.40%)	⬆️
mmaction/models/backbones/resnet3d_slowonly.py	78.57% <ø> (+3.57%)	⬆️
mmaction/models/heads/bbox_head.py	80.83% <ø> (+0.50%)	⬆️
...maction/models/roi_extractors/single_straight3d.py	77.58% <14.28%> (-5.75%)	⬇️
mmaction/core/evaluation/recall.py	11.42% <25.00%> (-0.34%)	⬇️
mmaction/models/backbones/resnet_tin.py	19.56% <25.00%> (-0.29%)	⬇️
...action/core/bbox/assigners/max_iou_assigner_ava.py	51.02% <50.00%> (ø)
mmaction/models/builder.py	55.26% <50.00%> (ø)
mmaction/models/heads/roi_head.py	28.26% <50.00%> (ø)
... and 3 more

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[dreamerlin]

Could you help to remove these lines : )

[congee524]

Could you help to remove these lines : )

Do these lines need to be removed?

[innerlee]

Hmm conflicts

[dreamerlin]

Could you help to remove these lines : )

Do these lines need to be removed?

emmmm, I mean use the same process

[dreamerlin]

tin_shift can not be simpily removed, you need to process it with the same step

[innerlee]

@dreamerlin good to go?