feat: introduce open telemetry support

[LarsSkovslund]

This PR introduces support for Open Telemetry.

To configure telemetry

builder
    .Services
    .AddOpenTelemetry()
    .WithMetrics(metrics =>
    {
        metrics
            .AddAspNetCoreInstrumentation()
            .AddHttpClientInstrumentation()
            .AddRuntimeInstrumentation();
    })
    .WithTracing(tracing =>
    {
        if (builder.Environment.IsDevelopment())
        {
            // We want to view all traces in development
            tracing.SetSampler(new AlwaysOnSampler());
        }

        tracing
            .AddAspNetCoreInstrumentation()
            .AddHttpClientInstrumentation()
            .AddSource(EventStoreDiagnostics.SourceName); // enable trace telemetry from event store and cqrs.
    });

To configure cosmos to emit otel telemetry, please see here. Cosmos client options are exposed on the EventStoreClientOptions.CosmosClientOptions.

[rickykaare]

Looks Awesome!