SCT: added read only support

I keep adding old formats to ensure interoperability with as many programs as possible...

This plugin adds read-only support for the Scitex SCT format only. This format is also supported by Photoshop in read and write (SCT test cases were created by Photoshop).

[Scitex HandShake Formats Specifications](/uploads/a3e213e48349d898b260375d6c052521/Scitex_HandShake_Formats.pdf)

autotests/CMakeLists.txt

@@ -72,6 +72,7 @@ kimageformats_read_tests(
     qoi
     ras
     rgb
+    sct
     tga
 )
 

autotests/read/sct/cmyk.sct.json

@@ -0,0 +1,11 @@
+[
+    {
+        "minQtVersion" : "6.8.0",
+        "fileName" : "cmyk.tif"
+    },
+    {
+        "maxQtVersion" : "6.7.99",
+        "unsupportedFormat" : true,
+        "comment" : "Qt versions lower than 6.8 do not support CMYK format so this test should be skipped."
+    }
+]