feat: Added RandomHorizontalFLip in TF

[SiddhantBahuguna]

This PR adds the following changes to the existing PR:

It adds RandomHorizontalFlip implementation in tensorflow. It transforms both the image and the target(with bboxes in relative coordinates)

      from doctr.transforms import RandomHorizontalFlip
       >>> import tensorflow as tf
       >>> transfo = RandomHorizontalFlip(p=0.5)
       >>> image = tf.random.uniform(shape=[64, 64, 3], minval=0, maxval=1)
       >>> target = {
        "boxes": np.array([[0.1, 0.1, 0.4, 0.5] ], dtype= np.float32),
        "labels": np.ones(1, dtype= np.int64)
        }
       >>> out = transfo(image, target)

It adds a unitest for the same

It adds RandomHorizontalFlip in the documentation

[codecov]

Codecov Report

Merging #779 (21ce24e) into main (e5ca2d5) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #779   +/-   ##
=======================================
  Coverage   95.99%   96.00%           
=======================================
  Files         130      130           
  Lines        4870     4882   +12     
=======================================
+ Hits         4675     4687   +12     
  Misses        195      195           

Flag	Coverage Δ
unittests	96.00% <100.00%> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
doctr/transforms/modules/tensorflow.py	93.05% <100.00%> (+0.63%)	⬆️

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[fg-mindee]

Thanks! Still need to add the entry in the documentation, but I added a few comments 👌

[fg-mindee]

Looks good! The failed test is not related and will be fixed by #781 (to be merged before this one)