crowddetector: Add tests for crowddetector filter

Change-Id: I77bb7c1c41622cbab30900631e0df156dd394837
faceoverlay: Add tests for faceoverlay filter

Change-Id: I0cb7853e58a8e0d099abff70e5840f10e4631ce4
chroma: Add tests for chroma filter

Change-Id: Ib520c462f932501854faa7a8aaddcb3b02de1131