feat: Added plot_samples support to visualize the images along with the targets

[SiddhantBahuguna]

This PR introduces the following modifications:

1. It adds a plot_sample script to visualize the images along with the targets
   

Any feedback is welcome :)

[SiddhantBahuguna]

When the script is run, I am facing the following error:

Traceback (most recent call last):
  File "/home/siddhant/Mindee/doctr/references/obj_detection/train_pytorch.py", line 289, in <module>
    main(args)
  File "/home/siddhant/Mindee/doctr/references/obj_detection/train_pytorch.py", line 189, in main
    plot_samples(images, targets, 4)
  File "/home/siddhant/Mindee/doctr/references/obj_detection/utils.py", line 31, in plot_samples
    cv2.rectangle(img, (int(box[0]), int(box[1])), (int(box[2]), int(box[3])), color, 1)
cv2.error: OpenCV(4.5.4-dev) :-1: error: (-5:Bad argument) in function 'rectangle'
> Overload resolution failed:
>  - Layout of the output array img is incompatible with cv::Mat
>  - Expected Ptr<cv::UMat> for argument 'img'
>  - Layout of the output array img is incompatible with cv::Mat
>  - Expected Ptr<cv::UMat> for argument 'img'

I am also unable to understand why out images.shape == (1024, 1024, 3) instead of (1024, 800, 3)
Thanks for the feedback !!

[fg-mindee]

Thanks for the PR! Let's remove the files that aren't related to the PR description :)

[codecov]

Codecov Report

Merging #704 (5f7d978) into main (cf97d9e) will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #704      +/-   ##
==========================================
+ Coverage   96.12%   96.17%   +0.04%     
==========================================
  Files         124      124              
  Lines        4648     4648              
==========================================
+ Hits         4468     4470       +2     
+ Misses        180      178       -2     

Flag	Coverage Δ
unittests	96.17% <ø> (+0.04%)	⬆️

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Impacted Files	Coverage Δ
doctr/models/detection/linknet/base.py	85.14% <0.00%> (ø)
doctr/models/recognition/predictor/pytorch.py	96.96% <0.00%> (+6.06%)	⬆️

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[fg-mindee]

A few other things as well in comment

[fg-mindee]

Let's move this after the dimension transpose

[fg-mindee]

Looks good to me! Would you mind increasing the line width of the box? It's barely visible when I try on my end 😅 (and perhaps add a screenshot of how it renders in the PR description for future references 👍 )

[fg-mindee]

Nice!