Auto create the Siril sequence with the pre-processed layers

[TomyCesaille]

Description

Create the Siril sequence with the pre-processed layers.

Would be creating a folder composition, with the result_S.fit, result_H.fit, result_O.fit etc... files and create the Siril sequence.

To think of this as part of a poto-siril process with a script template, so it's customizable (pre-registering + aligning the images are pre-work to do before dealing with the composition for instance).