feat: add common REST API sources

[Vasist10]

Adds garf-common-apis, a community library providing first-class GARF sources for OpenWeatherMap and CurrencyAPI built on top of the existing --source rest infrastructure.

This adds:

--source openweather with built-in API key handling and response normalization.
--source currencyapi with header-based authentication and flattened currency response rows.

Users no longer need to manage endpoint URLs, authentication parameters, or complex JSON response structures.

Added 25 mocked tests covering authentication, credential security, query parameter translation, response normalization, and error handling.

To test locally:

pip install -e "libs/community/common_apis[test]"
pytest libs/community/common_apis/tests/

[Vasist10]

Tried adding garf-common-apis with OpenWeatherMap and CurrencyAPI sources . Added authentication handling, response normalization, docs, examples, and tests.

Please have a look and let me know your feedback.
@AndreyMarkinPPC

[AndreyMarkinPPC]

Hi @Vasist10, thank you so much for contributing again!
I had the very same idea in #249 but never had any time for work on that.
Out of curiosity, are you using these two APIs (currency and weather) yourself or just referenced them here as an example?

[Vasist10]

Hi @Vasist10, thank you so much for contributing again! I had the very same idea in #249 but never had any time for work on that. Out of curiosity, are you using these two APIs (currency and weather) yourself or just referenced them here as an example?

I’ve used OpenWeatherMap before for weather data, but I haven’t personally used CurrencyAPI.