Add stream output for Agent

[Undertone0809]

Related to #833

Add stream output support for ToolAgent.

• ToolAgent Class:

  • Add stream parameter to the run method.
  • Implement logic to handle the stream parameter.
  • Modify the _run method to support streaming output.
  • Raise error if stream=True and output_schema is not provided.

• BaseAgent Class:

  • Add stream parameter to the run method.
  • Implement _run_stream method to handle streaming output.

• Example:

  • Update example/agent/tool_agent_usage.py to demonstrate the usage of agent.run(..., stream=True).

• Tests:

  • Add tests in tests/agents/test_tool_agent.py to verify the stream mode output functionality.

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Summary by CodeRabbit

• New Features

  • Introduced streaming capabilities for the agent, allowing real-time output during execution.
  • Enhanced the tool agent to process multiple responses dynamically.

• Bug Fixes

  • Added validation to ensure necessary parameters for streaming operations are provided.

• Tests

  • Added a new test to validate the tool agent's behavior in stream mode.