Support tensorrt custom plugin MMCVCornerPool

[qjqfl]

Support tensorrt custom plugin MMCVCornerPool, aligned with previous customized onnxruntime operation mmcv::MMCVCornerPool.

[codecov]

Codecov Report

Merging #1179 (9b67659) into master (23d7fc8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1179   +/-   ##
=======================================
  Coverage   67.99%   67.99%           
=======================================
  Files         159      159           
  Lines       10426    10426           
  Branches     1897     1897           
=======================================
  Hits         7089     7089           
  Misses       2968     2968           
  Partials      369      369           

Flag	Coverage Δ
unittests	67.99% <ø> (ø)

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[grimoire]

LGTM!

[OpenMMLab-Coodinator]

Hi @qjqfl ！First of all, we want to express our gratitude for your significant PR in this project. Your contribution is highly appreciated, and we are grateful for your efforts in helping improve this open-source project during your personal time. We believe that many developers will benefit from your PR.

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Thank you again for your contribution❤