ZipkinExporter: HttpClientFactory option

[CodeBlanch]

Changes

• Adds the same HttpClientFactory option we have on JaegerExporterOptions to ZipkinExporterOptions.
• Adds IHttpClientFactory integration when IDeferredTracerProviderBuilder is used.

TODOs

• CHANGELOG.md updated for non-trivial changes
• Unit tests

[codecov]

Codecov Report

Merging #2654 (aefbf9d) into main (f7d3227) will increase coverage by 0.93%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2654      +/-   ##
==========================================
+ Coverage   81.32%   82.25%   +0.93%     
==========================================
  Files         247      247              
  Lines        8664     8691      +27     
==========================================
+ Hits         7046     7149     +103     
+ Misses       1618     1542      -76     

Impacted Files	Coverage Δ
....Exporter.Jaeger/JaegerExporterHelperExtensions.cs	97.67% <100.00%> (+95.34%)	⬆️
...Telemetry.Exporter.Jaeger/JaegerExporterOptions.cs	90.47% <100.00%> (+5.47%)	⬆️
...rc/OpenTelemetry.Exporter.Zipkin/ZipkinExporter.cs	88.42% <100.00%> (ø)
....Exporter.Zipkin/ZipkinExporterHelperExtensions.cs	97.56% <100.00%> (+91.67%)	⬆️
...Telemetry.Exporter.Zipkin/ZipkinExporterOptions.cs	100.00% <100.00%> (ø)
...nTelemetry/Internal/OpenTelemetrySdkEventSource.cs	74.28% <0.00%> (+2.85%)	⬆️
...rc/OpenTelemetry.Exporter.Jaeger/JaegerExporter.cs	87.06% <0.00%> (+4.31%)	⬆️
...Exporter.Jaeger/Implementation/JaegerHttpClient.cs	44.00% <0.00%> (+44.00%)	⬆️

[mic-max]

Isn't 4.6.1 the lowest version we support now. I guess this comment is from when it was supported, and we no longer need to call it out

[CodeBlanch]

#2748