Refactor PanSharpening module to use FunctorImageFilter everywhere

Summary

This MR refactors PanSharpening module to use FunctorImageFilter.

Rationale

Avoids relying on TernaryFunctorImageFilter (either itk version or our own version). Gain performances by using the void operator()(Tout& out, ...) form.

Implementation Details

Appart from the removal of otb::ImageFusionBase which was a base class used only by BayesianFusionImageFilter, all modifications are internal to filters and do not change the API.

A small refactoring has been done PanSharpening application to avoid a compilation error (trying to convert the BayesianFusionImageFilter to the wrong instance of ImageToImageFilter). Maybe we could use the new RegisterPipeline() method here.

Copyright

The copyright owner is CNES and has signed the ORFEO ToolBox Contributor License Agreement.

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Check before merging:

• All discussions are resolved
• At least 2 votes from core developers, no vote.
• The feature branch is (reasonably) up-to-date with the base branch
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