Blender Git Loki

Cycles tests: Rework output messages

Made them closer to how GTest shows the output, so reading test logs
is easier now (at least feels more uniform).

Additionally now we know how much time tests are taking so can tweak
samples/resolution to reduce render time of slow tests.

It is now also possible to enable colored messages using magic
CYCLESTEST_COLOR environment variable. This makes it even easier to
visually grep failed/passed tests using `ctest -R cycles -V`.