Add an optional gRPC client-side load balancing for the otel exporter

[faustodavid]

Feature Request

What do you want to happen instead? What is the expected behavior?

Have an optional gRPC client-side load balancing for the otel exporter. https://docs.microsoft.com/en-us/aspnet/core/grpc/loadbalancing?view=aspnetcore-6.0

Describe alternatives you've considered.

Which alternative solutions or features have you considered?

Use the OtlpExportProtocol.HttpProtobuf, but then we won't have the performance advantages of using GRPC.

[faustodavid]

I was thinking maybe we could add a flag in the OtlpExporterOptions and use it to enable the client-side load balancing here:

https://github.com/open-telemetry/opentelemetry-dotnet/blob/e7f06afd51489e3047f167d9b7362aba512508c0/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExporterOptionsExtensions.cs#L45