Core functions for Polarimetric change analysis

[aalgo]

Core functions for Polarimetric change analysis added to processing_FD

• Added generalized_eigendecomp() function to perform the generalized eigendecomposition of two matrices.
• Added generate_pinc_pdec_RGBimages() to obtain the RGB images of the increase and decrease (p_inc and p_dec) [1].
• Added pytest functions for these two.

NOTE: I have also added a private utility function _apply_index_() to the module, as it is only used here, but we can consider wether it makes sense to move it to the utility package.

[1] Alonso González, A., López Martínez, C., Papathanassiou, K., & Hajnsek, I. (2020). Polarimetric SAR time series change analysis over agricultural areas. IEEE transactions on geoscience and remote sensing, 58(10), 7317-7330.

[emanuelegiorgi]

Thank you for the FD integrations, everything is nice and tests work fine. I agree to keep _applyindex() into processing_FD module.