MTIHighlightShadowFilter

A experimental highlight and shadow adjust filter for MetalPetal.

The implementation closely follows the highlight shadow operation in in GEGL/GIMP.

https://gitlab.gnome.org/GNOME/gegl/-/blob/42186a77b08431fb25851f88e03256bc347e9790/operations/common-gpl3+/shadows-highlights-correction.c

The GIMP implementation closely follows its counterpart in the Darktable photography software.

https://docs.gimp.org/2.10/en/gimp-filter-shadows-highlights.html