tests: rename color-shaper-matrix-test.c to color-icc-output-test.c

The new name better matches the contents of the test.

Currently the test creates output ICC profiles with matrix-shaper and
cLUT forms, and tests that basic color conversion from input to output
color space is correct.

The common theme in this test program is to create ICC profiles to be
used as output profiles. In the future this can include more kinds of
testing, e.g. linear blending. OTOH, this test program will always be
limited to SDR because HDR testing probably will not use ICC files.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>