OTLP Span arrays allow exporting null values + support for long arrays

[Austin-Tan]

Fixes #1843 .

1. For all string and supported primitive arrays (bool[], double[], long[]) allowed null values to be exported.
2. long arrays were not previously supported (only int[]), they are now.

• CHANGELOG.md updated for non-trivial changes

[codecov]

Codecov Report

Merging #1919 (14ef89b) into main (0208fd6) will increase coverage by 0.68%.
The diff coverage is 76.92%.

❗ Current head 14ef89b differs from pull request most recent head 7d2622e. Consider uploading reports for the commit 7d2622e to get more accurate results

@@            Coverage Diff             @@
##             main    #1919      +/-   ##
==========================================
+ Coverage   83.69%   84.38%   +0.68%     
==========================================
  Files         192      188       -4     
  Lines        6159     6117      -42     
==========================================
+ Hits         5155     5162       +7     
+ Misses       1004      955      -49     

Impacted Files	Coverage Δ
...metryProtocol/Implementation/ActivityExtensions.cs	86.30% <76.92%> (-0.60%)	⬇️
...rc/OpenTelemetry/Trace/TracerProviderBuilderSdk.cs	89.83% <0.00%> (-10.17%)	⬇️
...ZPages/Implementation/ZPagesExporterEventSource.cs	56.25% <0.00%> (-6.25%)	⬇️
...c/OpenTelemetry.Api/Trace/TracerProviderBuilder.cs	100.00% <0.00%> (ø)
...c/OpenTelemetry/Trace/TracerProviderBuilderBase.cs
...ing/Implementation/TracerProviderBuilderHosting.cs
...penTelemetry/Internal/ServiceProviderExtensions.cs
...s.Hosting/Trace/TracerProviderBuilderExtensions.cs
....Exporter.Jaeger/JaegerExporterHelperExtensions.cs	15.38% <0.00%> (+4.27%)	⬆️
....Exporter.Zipkin/ZipkinExporterHelperExtensions.cs	15.38% <0.00%> (+4.27%)	⬆️
... and 3 more

[cijothomas]

what happens to this null element ?

[Austin-Tan]

I removed the tests for nullable primtive type arrays like long?[] and double?[]. I think discussion of them is outside the scope of this PR

[CodeBlanch]

LGTM

[Oberon00]

I think 41b3eef needs to be reverted. Copying my comment from #1939 (comment):

Hi! The spec says that nulls in arrays are invalid and you should only allow them if the language does not make it possible to prevent them at compile-time. So explicitly using double? [] etc instead of double[] violates the spec. https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/common/common.md#attributes

null values SHOULD NOT be allowed in arrays.

only then does the spec also say:

However, if it is impossible to make sure that no null values are accepted (e.g. in languages that do not have appropriate compile-time type checking) ...

But in C# this only applies to strings.