[quantile regression project] add annual maxima osbervation from daily exponential. add sammple_r_function as argument to rmargin_from_nb_obs. add abstract extreme params

[EUROCODE][DRAWING PER REGION] modify test region eurocode. add test_ gev temporal bayesian. add stationary version for the Bayesian. refactor utils at the root, to root_uils to avoid weird import issues.

[EXTREME ESTIMATOR] refactor margin_fits folder. extreme estimator folder. and extreme_models folder

[SCM] improve visualization of the margin. add a 2D optional mask & visualization bounds to visualize a 2D margin

[SCM] improve empirical distribution visualization for slides. add single_massif_graph visualization

[EXTREME PARAMETERS] create an attribute undefined_parameters in ExtremeParameters object, to avoid crash when a shape is < 0 for point while we want to display

[EXTREME ESTIMATOR] add margin_fits folder. add gpd params & gpdmle_fit. refactor code to handle gev and gpd together

[SIMULATION] add constant estimators. handle graph plot of constant margin estimator (when the sampling margin was also constant)