[feature] GrasSim model integration

Context : The GrasSim grassland model was developped and implemented in R by Urbain Kokah. It predicts the daily growth of grass in a permanent pasture depending on weather data, soil conditions, management, and specie-specific parameters. The original implementation has been transcribed from R to Python and modified to use spatialized inputs.

GrasSim will be included in the agrivoltaics framework to extend the scope of the framework to a different type of agricultural land.

The steps of the integration of GrasSim in the PASE framework are :

• Add Model-specific parameters in INPUTS/CROPS
• Add Model functions in MODULES/CROPS
• Adapt data management/types of the model to work with the framework
• UsewWeather and light input from the framework in the model