feat: Added inference+post processing script for artefact detection

[SiddhantBahuguna]

This PR introduces the following :

-> It adds a bare evaluation script without post nms and post processing.
Any feedback is welcome :)

[codecov]

Codecov Report

Merging #728 (878bc83) into main (caa363c) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #728      +/-   ##
==========================================
- Coverage   96.04%   96.01%   -0.04%     
==========================================
  Files         129      129              
  Lines        4806     4794      -12     
==========================================
- Hits         4616     4603      -13     
- Misses        190      191       +1     

Flag	Coverage Δ
unittests	96.01% <ø> (-0.04%)	⬇️

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Impacted Files	Coverage Δ
doctr/models/detection/predictor/tensorflow.py	94.44% <0.00%> (-5.56%)	⬇️
doctr/io/pdf.py	98.33% <0.00%> (-1.67%)	⬇️
doctr/models/detection/linknet/pytorch.py	97.82% <0.00%> (-0.26%)	⬇️
doctr/models/recognition/predictor/tensorflow.py	91.17% <0.00%> (ø)
doctr/models/builder.py	97.36% <0.00%> (+0.87%)	⬆️

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[fg-mindee]

Added a few comments!

[fg-mindee]

Still some things to handle

[fg-mindee]

Looks good!