Feat/slice intersect multi series

[ymatzkevich]

Checklist before merging this PR:

• Mentioned all issues that this PR fixes or addresses.
• Summarized the updates of this PR under Summary.
• Added an entry under Unreleased in the Changelog.

Fixes #2042.

Summary

Other Information

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.06%. Comparing base (d909589) to head (8e3921d).

Files with missing lines	Patch %	Lines
darts/timeseries.py	90.90%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2591      +/-   ##
==========================================
- Coverage   94.14%   94.06%   -0.09%     
==========================================
  Files         139      139              
  Lines       14884    14895      +11     
==========================================
- Hits        14013    14011       -2     
- Misses        871      884      +13     

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