Updated search_datasets tool using gemini search + the default

[SubhadityaMukherjee]

• Redefined the search_datasts tool while using gemini to also do a "google search" using gemini and not just look at the dataset index when doing a search. This can be tested using "eclair-client --tool search-datasets --query "tree cover datasets" --use-gemini" after running eclair-server and gemini-cli (following the current documentation)

• Also updated the required packages so we can use 'uv' as the venv/package manager.