Feature interp

[CentofantiEze]

This branch introduces the SED interpolation feature. Latest modifications allows using directly the interpolation while optimising the model instead of having to create outside an interpolated SED dataset.

It adds new click options:

• interp_pts_per_bin int in {0,1,2,3}. Number of points per bin to add during the interpolation process.
• extrapolate bool. Whether extrapolation is performed or not.
• SED_interp_kind str in {'linear', 'cubic'}. Type of interpolation for the SED.
• n_bins_gt int. Number of bins used for the ground truth poly PSF generation.

[tobias-liaudat]

Some lines in the project_DD_features are not very clear (both with double inline list comprehensions ), it would be better to make them simpler, but it is not at all required

[tobias-liaudat]

This PR resolves #25, resolves #28, resolves #29, resolves #31 .