[monitor] Make AzureMonitor exporter classes and options public

[mattsains-msft]

Fixes:
#55206
#55012

[github-actions]

API Change Check

APIView identified API level changes in this PR and created the following API reviews

Azure.Monitor.OpenTelemetry.Exporter

[Copilot]

Pull request overview

This pull request makes the Azure Monitor exporter classes and configuration options public to address two feature requests. Previously, the AzureMonitorTraceExporter, AzureMonitorMetricExporter, and AzureMonitorLogExporter classes were internal, forcing users to only use extension methods from AzureMonitorExporterExtensions. Additionally, configuration options like EnablePerfCounters and EnableStandardMetrics were internal. Making these public enables users to create custom processor pipelines and control telemetry collection behavior.

Changes:

• Made three exporter classes public: AzureMonitorTraceExporter, AzureMonitorMetricExporter, and AzureMonitorLogExporter
• Made two configuration properties public: EnablePerfCounters and EnableStandardMetrics in AzureMonitorExporterOptions
• Added XML documentation comments to the newly public constructors and classes
• Updated API listing files for all target frameworks to reflect the new public API surface

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
AzureMonitorTraceExporter.cs	Changed class from internal to public, added XML documentation for the class and public constructor
AzureMonitorMetricExporter.cs	Changed class from internal to public, added XML documentation for the class and public constructor
AzureMonitorLogExporter.cs	Changed class from internal to public, updated class summary documentation
AzureMonitorExporterOptions.cs	Changed EnableStandardMetrics and EnablePerfCounters properties from internal to public
Azure.Monitor.OpenTelemetry.Exporter.netstandard2.0.cs	Updated API listing to include new public exporter classes and properties
Azure.Monitor.OpenTelemetry.Exporter.netstandard2.0..cs	Updated API listing to include new public exporter classes and EnablePerfCounters property (incomplete)
Azure.Monitor.OpenTelemetry.Exporter.net8.0.cs	Updated API listing to include new public exporter classes and properties
Azure.Monitor.OpenTelemetry.Exporter.net10.0.cs	Updated API listing to include new public exporter classes and properties