add docred and docred_revisited datasets

[ArneBinder]

TODO:

• add BASE_DATASET_REVISIONs
• add tests
• add requirements.txts
• add dataset cards, i.e. README.mds

[codecov]

Codecov Report

Attention: 232 lines in your changes are missing coverage. Please review.

Comparison is base (e2803b2) 93.07% compared to head (c2dfce5) 80.08%.

Files	Patch %	Lines
dataset_builders/pie/docred/docred.py	28.83%	116 Missing ⚠️
..._builders/pie/docred_revisited/docred_revisited.py	28.83%	116 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #33       +/-   ##
===========================================
- Coverage   93.07%   80.08%   -13.00%     
===========================================
  Files          17       19        +2     
  Lines        1286     1612      +326     
===========================================
+ Hits         1197     1291       +94     
- Misses         89      321      +232     

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