Get DRIAS/Explore2 climatic data

The airGRccia package already contains a lot of useful function for processing climate data including download and aggregation at basin scale:

• List of netCDF file from DRIAS2020/Explore2 database
• Create a stars object for one DRIAS projection
• Read climate data from NetCDF files
• Extract cell values from a climate dataset

Several strategies are possible for integrating these functionalities:

• add an import dependency in RADIS to airGRccia
• migrate all related functions into RADIS and add an import dependency to RADIS into airGRccia
• create a separate package that process French climate data (maybe including #4 (closed)) and let RADIS and airGRccia depend on it

I personally prefer the last solution which is more modular and allows to create a finalized package that can quickly be proposed to https://github.com/inrae and used by a lot of people that work with climate data.