Improve grib support

[sbrunato]

• Add netcdf4 and cfgrib as dependencies
• add .grib file extension to a new eodag-cube constant of accepted raster file extensions, as it not known by GDAL and rasterio.drivers.driver_from_extension() (only .grb and .grb2 are recognized)
• update https://eodag.readthedocs.io/en/latest/tutos.html using eodag-cube, see update tutorials using eodag-cube eodag#1385 for more details

[amarandon]

@sbrunato As far as this repo is concerned, my work is ready for review. Do you mind if we remove the bullet point about docs from this issue since there's a dedicated issue in eodag repo?