Improve test ICC profiles, switch default rendering intent

On average for all kinds of applications on all kinds of displays, the perceptual rendering intent should produce the most desirable results. Switch the default rendering intent to perceptual.

However, first we need to fix the ICC profiles generated in the test suite to avoid test failures. How they were broken and what the fix is are complicated, see the commit message. I also took the opportunity to remove some hardcoded color transformation matrices from the test setups, they can just as well be derived from the primaries and the white point.

I've locally verified the test suite passes on each patch of the series.

cc @leandrohrb