[sdk] Add ActivityExportProcessorOptions and clean up MetricReaderOptions

[CodeBlanch]

[Originally part of #5400]

Changes

• Adds ActivityExportProcessorOptions for tracing. This brings tracing in line with logging (LogRecordExportProcessorOptions) and metrics (MetricReaderOptions).
• Fixes options registrations so that all three signals work the same way:
  • Logging users can access\bind LogRecordExportProcessorOptions (already in place) or BatchExportLogRecordProcessorOptions (already in place)
  • Metrics users can access\bind MetricReaderOptions (already in place) or PeriodicExportingMetricReaderOptions (added on this pr)
  • Tracing users can access\bind ActivityExportProcessorOptions (added on this pr) or BatchExportActivityProcessorOptions (already in place)

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
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Attention: Patch coverage is 40.90909% with 13 lines in your changes are missing coverage. Please review.

Project coverage is 84.61%. Comparing base (6250307) to head (397c17d).
Report is 118 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5423      +/-   ##
==========================================
+ Coverage   83.38%   84.61%   +1.23%     
==========================================
  Files         297      282      -15     
  Lines       12531    12116     -415     
==========================================
- Hits        10449    10252     -197     
+ Misses       2082     1864     -218     

Flag	Coverage Δ
unittests	?
unittests-Solution-Experimental	84.61% <40.90%> (?)
unittests-Solution-Stable	84.34% <40.90%> (?)

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

Files	Coverage Δ
src/OpenTelemetry/Metrics/MetricReaderOptions.cs	100.00% <100.00%> (ø)
...lder/ProviderBuilderServiceCollectionExtensions.cs	91.30% <71.42%> (-8.70%)	⬇️
...nTelemetry/Trace/ActivityExportProcessorOptions.cs	0.00% <0.00%> (ø)

... and 55 files with indirect coverage changes

[CodeBlanch]

Why add this now?

Today we have these options essentially exposed directly on OtlpExporterOptions:

opentelemetry-dotnet/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExporterOptions.cs

Lines 137 to 147 in f34fce5

	/// <summary>
	/// Gets or sets the export processor type to be used with the OpenTelemetry Protocol Exporter. The default value is <see cref="ExportProcessorType.Batch"/>.
	/// </summary>
	/// <remarks>Note: This only applies when exporting traces.</remarks>
	public ExportProcessorType ExportProcessorType { get; set; } = ExportProcessorType.Batch;
	/// <summary>
	/// Gets or sets the BatchExportProcessor options. Ignored unless ExportProcessorType is Batch.
	/// </summary>
	/// <remarks>Note: This only applies when exporting traces.</remarks>
	public BatchExportProcessorOptions<Activity> BatchExportProcessorOptions { get; set; }

Originally that made sense when we only had tracing. But now we have logging and metrics which also use OtlpExporterOptions but need different settings. For metrics we have MetricReaderOptions. For logging we have LogRecordExportProcessorOptions.

On #5400 we're adding a new UseOtlpExporter method. Instead of bringing forward this mess that extension will use ActivityExportProcessorOptions so it mirrors logging & metrics and hides away these two options which really should have never been exposed.

/cc @alanwest

[alanwest]

I think we should mark the old options obsolete.

[CodeBlanch]

Just in case anyone is wondering...

• There wasn't a CHANGELOG update on this PR. The reason for that is ActivityExportProcessorOptions can't be used for much right now. @alanwest and I decided we should do follow-up PRs to use ActivityExportProcessorOptions with OTLP & Zipkin and then we can add the entry.

• There aren't tests on this PR. We don't have direct tests for LogRecordExportProcessorOptions either. It is only tested via OTLP tests. So I'll add similar tests for ActivityExportProcessorOptions on [otlp] UseOtlpExporter cross-cutting extension #5400