Add fredapi tool to search Federal Reserve Economic Data

[oopslgy]

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#252

-This PR introduces an enhanced FredApiTool integration for accessing FRED (Federal Reserve Economic Data) with expanded functionality and improved performance. The tool provides access to macroeconomic indicators, supporting data search, time-series analysis.
Multi-Mode Data Access
SEARCH: Advanced dataset search with filters (frequency, units, etc.)
DETAIL: Time-series value retrieval with date-range filtering
-Requirements
fredapi library (install via pip install fredapi)
FRED API key (free registration at https://fred.stlouisfed.org/docs/api/api_key.htm)

Please provide the path of test files and submit screenshots or files of the test results(fill in as needed): | 请填写测试文件路径并提供测试结果截图或文件(按需填写):

-tests/test_agentuniverse/unit/agent/action/tool/test_fredapi_tool.py

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[oopslgy]

#252