🔧 Synchronize list splitting behaviour in need and needextend directives

[chrisjsewell]

NeedextendDirective had a different function than NeedDirective, for splitting lists from directive options.

This PR combines the two, to make the behaviour consistent.

[codecov]

Codecov Report

Attention: Patch coverage is 91.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 88.16%. Comparing base (4e10030) to head (33d41be).
Report is 101 commits behind head on master.

Files with missing lines	Patch %	Lines
sphinx_needs/api/need.py	93.75%	1 Missing ⚠️
sphinx_needs/directives/needextend.py	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1385      +/-   ##
==========================================
+ Coverage   86.87%   88.16%   +1.28%     
==========================================
  Files          56       60       +4     
  Lines        6532     7117     +585     
==========================================
+ Hits         5675     6275     +600     
+ Misses        857      842      -15     

Flag	Coverage Δ
pytests	88.16% <91.66%> (+1.28%)	⬆️

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[ubmarco]

Thanks for cleaning this up.

[ubmarco]

This looks like there are multiple splitting characters. Maybe mention this in https://sphinx-needs.readthedocs.io/en/latest/filter.html#filter-options. The pages currently says For :status:, :tags: and :types: values are separated by “;”.. Have not found another mention of this.

[chrisjsewell]

Personally I would rather there were not these multiple characters, but that would be back breaking 🤷
will look at docs in separate PR