[zipkin] Switch to TagWriter for handling of tags/attributes

[CodeBlanch]

Follow-up to #5476
Relates to #5475

Changes

• Switch from TagTransformer to TagWriter design in ZipkinExporter project

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes

[codecov]

Codecov Report

Attention: Patch coverage is 62.50000% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 85.65%. Comparing base (6250307) to head (02bad89).
Report is 206 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5590      +/-   ##
==========================================
+ Coverage   83.38%   85.65%   +2.27%     
==========================================
  Files         297      271      -26     
  Lines       12531    11377    -1154     
==========================================
- Hits        10449     9745     -704     
+ Misses       2082     1632     -450     

Flag	Coverage Δ
unittests	?
unittests-Solution-Experimental	85.65% <62.50%> (?)
unittests-Solution-Stable	85.38% <62.50%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...metry.Exporter.Zipkin/Implementation/ZipkinSpan.cs	96.15% <50.00%> (+1.15%)	⬆️
....Exporter.Zipkin/Implementation/ZipkinTagWriter.cs	63.63% <63.63%> (ø)

... and 99 files with indirect coverage changes