[Enhance] Support mim

[wHao-Wu]

Thanks for your contribution and we appreciate it a lot. The following instructions would make your pull request more healthy and more easily get feedback. If you do not understand some items, don't worry, just make the pull request and seek help from maintainers.

Motivation

• Support MIM

[codecov]

Codecov Report

Merging #782 (b74fea7) into master (1b2e64c) will not change coverage.
The diff coverage is n/a.

❗ Current head b74fea7 differs from pull request most recent head c7c2def. Consider uploading reports for the commit c7c2def to get more accurate results

@@           Coverage Diff           @@
##           master     #782   +/-   ##
=======================================
  Coverage   48.94%   48.94%           
=======================================
  Files         208      208           
  Lines       15884    15884           
  Branches     2538     2538           
=======================================
  Hits         7774     7774           
  Misses       7608     7608           
  Partials      502      502           

Flag	Coverage Δ
unittests	48.94% <ø> (ø)

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

Impacted Files	Coverage Δ
mmdet3d/core/visualizer/show_result.py	66.38% <ø> (ø)

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[ZwwWayne]

May test the compatibility with MIM.

[wHao-Wu]

@ZwwWayne @zhouzaida
The test of compatibility between mmdet3d and mim is completed successfully.

[zhouzaida]

LGTM