feat(agents): add agent naming functionality (#1922)

# What does this PR do?
Allow users to name an agent and use the name in telemetry instead of
relying on randomly generated agent_ids. This improves the developer
experience by making it easier to find specific agents in telemetry
logs.

Closes #1832

## Test Plan

- Added tests to verify the agent name is properly stored and retrieved
- Ran `uv run -- pytest -v
tests/integration/telemetry/test_telemetry.py::test_agent_name_filtering`
from the root of the project and made sure the tests pass
- Ran `uv run -- pytest -v
tests/integration/telemetry/test_telemetry.py::test_agent_query_spans`
to verify existing code without agent names still works correctly

## Use Example
```
agent = Agent(
    llama_stack_client, 
    model=text_model_id, 
    name="CustomerSupportAgent",  # New parameter
    instructions="You are a helpful customer support assistant"
)
session_id = agent.create_session(f"test-session-{uuid4()}")
```

## Implementation Notes
- Agent names are optional string parameters with no additional
validation
- Names are not required to be unique - multiple agents can have the
same name
- The agent_id remains the unique identifier for an agent

---------

Co-authored-by: raghotham <raghotham@gmail.com>

docs/_static/llama-stack-spec.yaml

@@ -3686,18 +3686,28 @@ components:
           default: 10
         model:
           type: string
+          description: >-
+            The model identifier to use for the agent
         instructions:
           type: string
+          description: The system instructions for the agent
+        name:
+          type: string
+          description: >-
+            Optional name for the agent, used in telemetry and identification
         enable_session_persistence:
           type: boolean
           default: false
+          description: Whether to persist session data
         response_format:
           $ref: '#/components/schemas/ResponseFormat'
+          description: Optional response format configuration
       additionalProperties: false
       required:
         - model
         - instructions
       title: AgentConfig
+      description: Configuration for an agent.
     AgentTool:
       oneOf:
         - type: string