Intermediate checkpointing for sequential calibration

[sugunav14]

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Codecov Report

❌ Patch coverage is 93.84615% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.30%. Comparing base (ada1e26) to head (c926e3e).

Files with missing lines	Patch %	Lines
...t/torch/quantization/utils/activation_collector.py	92.42%	5 Missing ⚠️
modelopt/torch/quantization/conversion.py	66.66%	2 Missing ⚠️
modelopt/torch/quantization/model_calib.py	92.85%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1152      +/-   ##
==========================================
+ Coverage   70.18%   70.30%   +0.12%     
==========================================
  Files         230      231       +1     
  Lines       26080    26195     +115     
==========================================
+ Hits        18304    18417     +113     
- Misses       7776     7778       +2     

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