Fix opentelemetry adapter (#510)

# What does this PR do?

This PR fixes some of the issues with our telemetry setup to enable logs
to be delivered to opentelemetry and jaeger. Main fixes
1) Updates the open telemetry provider to use the latest oltp exports
instead of deprected ones.
2) Adds a tracing middleware, which injects traces into each HTTP
request that the server recieves and this is going to be the root trace.
Previously, we did this in the create_dynamic_route method, which is
actually not the actual exectuion flow, but more of a config and this
causes the traces to end prematurely. Through middleware, we plugin the
trace start and end at the right location.
3) We manage our own methods to create traces and spans and this does
not fit well with Opentelemetry SDK since it does not support provide a
way to take in traces and spans that are already created. it expects us
to use the SDK to create them. For now, I have a hacky approach of just
maintaining a map from our internal telemetry objects to the open
telemetry specfic ones. This is not the ideal solution. I will explore
other ways to get around this issue. for now, to have something that
works, i am going to keep this as is.

Addresses: #509

llama_stack/providers/inline/eval/meta_reference/eval.py

@@ -72,7 +72,7 @@ class MetaReferenceEvalImpl(Eval, EvalTasksProtocolPrivate):
         key = f"{EVAL_TASKS_PREFIX}{task_def.identifier}"
         await self.kvstore.set(
             key=key,
-            value=task_def.json(),
+            value=task_def.model_dump_json(),
         )
         self.eval_tasks[task_def.identifier] = task_def