CmykSimulation converts process colour to an output intent's CMYK
through a color::CmykConversion: sRGB colours, and CIE XYZ relative to
the D50 PCS white (color::PCS_WHITE) for Lab and ICCBased colours.
CmykSimulation::new keeps the moxcms conversion from pdfcraft #2770,
which takes XYZ on through its ProPhoto hub; with_conversion takes a
caller's, so a crate can separate with its own colour management.
crates/pdf/tests/plates.rs adapts #2770's plate tests to the raster
path: process, spot, DeviceN, All/None, ICC CMYK, gray and RGB colours,
images, shadings, uncoloured patterns, soft masks, OP/op/OPM, the ink
sink, output-intent simulation with #2770's synthetic ICC profiles, and
a caller's conversion. The ledger and NOTICE name the pull request.
Co-authored-by: Guillem Hermida <66697068+guillehr2@users.noreply.github.com>