tests: move functions that create ICC profiles to lcms_util.c

We'll need to craft ICC profiles in the CM&HDR protocol implementation
tests. So move it from color-icc-output-test.c to the LittleCMS helper
in our test suite.

This also removes some unused headers from color-icc-output-test.c, as
we've moved a bunch of code to the LittleCMS helper.

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>