Support exporting TensorRT serialized engine in CLI tools

[zhiqwang]

We provide a Python CLI tools to export the TensorRT serialized engine

python tools/export_model.py --checkpoint_path [path/to/your/best.pt] --include engine

Close #322

[codecov]

Codecov Report

Merging #326 (2e8d929) into main (31ab550) will not change coverage.
The diff coverage is n/a.

❗ Current head 2e8d929 differs from pull request most recent head 699ca6b. Consider uploading reports for the commit 699ca6b to get more accurate results

@@           Coverage Diff           @@
##             main     #326   +/-   ##
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  Coverage   95.38%   95.38%           
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  Files          11       11           
  Lines         759      759           
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  Hits          724      724           
  Misses         35       35           

Flag	Coverage Δ
unittests	95.38% <ø> (ø)

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