Update UseOpenTelemetry for latest genai spec updates

[stephentoub]

• Events are now expected to be emitted as body fields, and the newly-recommended way to achieve that is via ILogger. So UseOpenTelemetry now takes an optional logger that it uses for emitting such data.
• I restructured the implementation to reduce duplication.
• Added logging of response format and seed.
• Added ChatOptions.TopK, as it's one of the parameters considered special by the spec.
• Updated the Azure.AI.Inference provider name to match the convention and what the library itself uses
• Updated the OpenAI client to use openai regardless of the kind of the actual client being used, per spec and recommendation

Closes #5523

Microsoft Reviewers: Open in CodeFlow

[tarekgh]

    _meter = new(name);

I am wondering if OpenTelemetryChatClient will be created many times? I am asking because it creates ActivitySource, Logger, and Meter and dispose them when the object is not in use any more. If it is expected the component is used inside a container, would it be better to use IMeterFactory for instance like:

var meterFactory = services.GetRequiredService();
var meter = meterFactory.Create("HatCo.Store");

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Refers to: src/Libraries/Microsoft.Extensions.AI/ChatCompletion/OpenTelemetryChatClient.cs:67 in 4594124. [](commit_id = 4594124, deletion_comment = False)

[tarekgh]

Reviewed the usage of the telemetry stuff and left a couple of questions. LGTM!

[stephentoub]

I am wondering if OpenTelemetryChatClient will be created many times? I am asking because it creates ActivitySource, Logger, and Meter and dispose them when the object is not in use any more. If it is expected the component is used inside a container, would it be better to use IMeterFactory for instance like:

It might be; it'll end up typically depending on how instances are registered in DI, whether as singleton or scoped.

It could take an IMeterFactory, but that'd require adding a ctor parameter, and I don't see us doing that in many places. Is it recommended? It also wouldn't help with the ActivitySource.