[Feature] Support auto import modules from registry

[Z-Fran]

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Motivation

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Modification

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BC-breaking (Optional)

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Checklist

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• Pre-commit or linting tools indicated in CONTRIBUTING.md are used to fix the potential lint issues.
• Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
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[codecov]

Codecov Report

Base: 88.80% // Head: 88.98% // Increases project coverage by +0.18% 🎉

Coverage data is based on head (156cdc3) compared to base (1431beb).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff             @@
##           dev-1.x    #1621      +/-   ##
===========================================
+ Coverage    88.80%   88.98%   +0.18%     
===========================================
  Files          399      400       +1     
  Lines        26031    26079      +48     
  Branches      4038     4043       +5     
===========================================
+ Hits         23116    23206      +90     
+ Misses        2016     1974      -42     
  Partials       899      899              

Flag	Coverage Δ
unittests	88.98% <100.00%> (+0.18%)	⬆️

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

Impacted Files	Coverage Δ
mmedit/__init__.py	96.55% <100.00%> (+1.09%)	⬆️
mmedit/apis/inferencers/inference_functions.py	77.56% <100.00%> (ø)
mmedit/edit.py	91.76% <100.00%> (ø)
mmedit/registry.py	100.00% <100.00%> (ø)
mmedit/apis/inferencers/colorization_inferencer.py	76.31% <0.00%> (ø)
mmedit/datasets/transforms/aug_shape.py	96.12% <0.00%> (+0.64%)	⬆️
mmedit/apis/inferencers/mmedit_inferencer.py	90.90% <0.00%> (+0.66%)	⬆️
...it/models/editors/stylegan1/stylegan1_generator.py	88.80% <0.00%> (+2.98%)	⬆️
...odels/editors/stylegan1/stylegan1_discriminator.py	97.87% <0.00%> (+8.51%)	⬆️
... and 3 more

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