Registration rework part I

Description

This merge request addresses:

• splitting the file registration.c in different files for easier maintenance
• fixing some remaining issues from drizzle that affect the same files
• fixing astrometric registration reference point

Changes Made

• registration/registratrion.c is split in:
  • registration/registration.c which addresses the generic registration workflow
  • gui/registration.c/.h which deal with all the gtk machinery/callbacks and idle function
  • registration/shift_methods.c which collects the "simple" registration methods such as register_shift_dft, register_shift_fwhm and register_kombat
• fixed an issue where images with a CFA pattern were not having the non-green pixels interpolated prior to registration
• fixed an issue where images where not correctly aligned with drizzle when sequence had a meridian flip (#1289 (closed))
• fixed reference point coordinates as per opencv convention in intrisic matrix calculation (astrometric reg)
• fixed image info not being updating after platesolve

Related Issues

see #1285, #1289 (closed) . No changes required in Changelog

Merge Request Checklists

• Code follows project coding guidelines and its checklist
• I have submitted a MR in the documentation repository if required
• I have updated Changelog and NEWS, listing the related issues.
• If my MR introduces new dependencies, I have run all the CIs, even the optional (manual) jobs.