feat: Updating the Tracing implementation and updating BaseAgent.runLive

[copybara-service]

feat: Updating the Tracing implementation and updating BaseAgent.runLive

This update should make the java tracing consistent with Python ADK:

1. BaseAgent.java:

   • The runAsync and runLive methods have been modified to create the InvocationContext before starting the tracing span.
   • The span name for agent invocations has been changed from "agent_run [<agent name>]" to "invoke_agent <agent name>".
   • A new Tracing.traceAgentInvocation method is now called to add initial tracing attributes for the agent invocation.
   • In runLive, the runLiveImpl execution is now wrapped with calls to beforeAgentCallback and afterAgentCallback to ensure proper tracing of these lifecycle events.

2. Tracing.java:

   • The OpenTelemetry tracer name has been updated from "com.google.adk" to "gcp.vertex.agent".
   • A new traceAgentInvocation method has been added to set standard attributes for agent invocation spans, including gen_ai.operation.name, gen_ai.agent.description, gen_ai.agent.name, and gen_ai.conversation.id.
   • Attribute keys used in traceToolCall, traceToolResponse, traceCallLlm, and traceSendData have been updated to use the "gcp.vertex.agent." prefix instead of "adk." or "com.google.adk".
   • The serialization of message content (like tool call arguments, tool responses, and data) is now guarded by the CAPTURE_MESSAGE_CONTENT_IN_SPANS flag. When disabled, empty JSON objects are recorded instead.
   • traceToolResponse now includes logic to extract and trace the tool_call.id and the tool response content from FunctionResponse objects.
   • traceCallLlm now captures additional LLM request and response details, such as gen_ai.request.top_p, gen_ai.request.max_tokens, gen_ai.usage.input_tokens, gen_ai.usage.output_tokens, and gen_ai.response.finish_reasons.