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>

llama_stack/apis/agents/agents.py

@@ -225,8 +225,18 @@ class AgentConfigCommon(BaseModel):
 
 @json_schema_type
 class AgentConfig(AgentConfigCommon):
+    """Configuration for an agent.
+
+    :param model: The model identifier to use for the agent
+    :param instructions: The system instructions for the agent
+    :param name: Optional name for the agent, used in telemetry and identification
+    :param enable_session_persistence: Optional flag indicating whether session data has to be persisted
+    :param response_format: Optional response format configuration
+    """
+
     model: str
     instructions: str
+    name: Optional[str] = None
     enable_session_persistence: Optional[bool] = False
     response_format: Optional[ResponseFormat] = None