SSDM-946: Extending tests for testing overlays

...onicPlateImageDropboxTest/1_1_GFP_OverlayDAPI_Default.png

...lateImageDropboxTest/1_2_CY3_Overlay2GFP_DAPI_256x256.png

...onicPlateImageDropboxTest/2_1_CY3_Overlay2GFP_Default.png

...ateImageDropboxTest/Platonic-Plate/bPLATE_wA1_s4_cRGB.png

...ateImageDropboxTest/Platonic-Plate/bPLATE_wA1_s5_cRGB.png

...ateImageDropboxTest/Platonic-Plate/bPLATE_wA1_s6_cRGB.png

...e16BitImageDropboxTest/1_2_Merged_Overlay2CY3_256x256.png

...t-data/Simple16BitImageDropboxTest/2_1_Merged_Default.png

...mageDropboxTest/PLATE-16-BIT/PLATE-16-BIT_A01_04_DAPI.png

...ImageDropboxTest/PLATE-16-BIT/PLATE-16-BIT_A01_04_GFP.png

...s/screening/systemtests/AbstractImageDropboxTestCase.java

...creening/systemtests/AbstractScreeningSystemTestCase.java

.../screening/systemtests/PlatonicPlateImageDropboxTest.java

...is/screening/systemtests/Simple16BitImageDropboxTest.java