add unit test for 8ppB, previously white mode #253

Job	Run time
build-arduino (release-v4.4, weather)	2m 56s
format-check	1m 16s
build (release-v4.4, calibration_helper)	2m 6s
build (release-v4.4, demo)	2m 7s
build (release-v4.4, dragon)	2m 5s
build (release-v4.4, grayscale_test)	2m 10s
build (release-v4.4, www-image)	2m 10s
build (release-v5.1, calibration_helper)	2m 11s
build (release-v5.1, demo)	2m 8s
build (release-v5.1, dragon)	2m 15s
build (release-v5.1, grayscale_test)	2m 7s
build (release-v5.1, www-image)	2m 16s
build (release-v5.2, calibration_helper)	2m 18s
build (release-v5.2, demo)	2m 21s
build (release-v5.2, dragon)	2m 6s
build (release-v5.2, grayscale_test)	2m 16s
build (release-v5.2, www-image)	2m 18s
build (release-v5.3, calibration_helper)	2m 12s
build (release-v5.3, demo)	2m 21s
build (release-v5.3, dragon)	2m 12s
build (release-v5.3, grayscale_test)	2m 18s
build (release-v5.3, www-image)	2m 20s
build (release-v5.1, screen_diag)	2m 8s
	50m 37s

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