feat: add nutrient extractor

[raphael0202]

Add the nutrient extractor model.
For every new image, we run the model inference and save the raw prediction in ImagePrediction table.
If the prediction is not empty (=if some values were found), we create a prediction. If the product has no nutrient, an insight is created.

A new API route was not added, it will be dealt with in a subsequent PR.

[codecov]

Codecov Report

Attention: Patch coverage is 48.67925% with 136 lines in your changes missing coverage. Please review.

Project coverage is 54.65%. Comparing base (463a1f1) to head (91ef024).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
robotoff/prediction/nutrition_extraction.py	57.44%	80 Missing ⚠️
robotoff/workers/tasks/import_image.py	8.82%	31 Missing ⚠️
robotoff/cli/main.py	13.33%	13 Missing ⚠️
robotoff/insights/importer.py	62.50%	6 Missing ⚠️
robotoff/triton.py	14.28%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1437      +/-   ##
==========================================
- Coverage   54.79%   54.65%   -0.14%     
==========================================
  Files          84       85       +1     
  Lines        8359     8625     +266     
==========================================
+ Hits         4580     4714     +134     
- Misses       3779     3911     +132     

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