feat: Added dedicated evaluation scripts for text detection

[fg-mindee]

This PR introduces the following modifications:

• adds scripts to evaluate text detection models on supported datasets
• adds the perf report as a .csv

I'll have to open another PR for text recognition because the crop needs to be made live efficiently. Those PRs aim at speeding up evaluation runs for models once they are trained

Any feedback is welcome!

[codecov]

Codecov Report

Merging #761 (e1b4f16) into main (56a5830) will increase coverage by 0.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #761      +/-   ##
==========================================
+ Coverage   96.22%   96.28%   +0.06%     
==========================================
  Files         129      129              
  Lines        4764     4764              
==========================================
+ Hits         4584     4587       +3     
+ Misses        180      177       -3     

Flag	Coverage Δ
unittests	96.28% <ø> (+0.06%)	⬆️

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Impacted Files	Coverage Δ
doctr/transforms/modules/base.py	94.44% <0.00%> (ø)
doctr/models/_utils.py	98.79% <0.00%> (+1.20%)	⬆️
doctr/models/recognition/predictor/tensorflow.py	97.05% <0.00%> (+5.88%)	⬆️

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[charlesmindee]

Thanks!