Support prediction regex match by setting the operator as a postproce…

[antonpibm]

This PR adds the ability to extract parts of the predictions with regex and compare them with a reference
The regex extraction only applies for the prediction
The to_list_by_comma only happens for the refernce
Adding the Jaccard index for comparing the two groups

After the regex processor is added it can be configured, example: processors.prediction_regex_parser[regex=\d+]

[elronbandel]

Great contribution @antonpibm !

[codecov]

Codecov Report

Attention: Patch coverage is 46.15385% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 92.03%. Comparing base (5783d76) to head (31c4d7b).
Report is 33 commits behind head on main.

Files	Patch %	Lines
src/unitxt/metrics.py	46.15%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #792      +/-   ##
==========================================
+ Coverage   91.48%   92.03%   +0.55%     
==========================================
  Files         100      103       +3     
  Lines       10169    10562     +393     
==========================================
+ Hits         9303     9721     +418     
+ Misses        866      841      -25     

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