Move the scenegraph lancelot test into the new baseline test category

Follow the new structure and naming scheme from qtbase.

Pick-to: 6.2
Change-Id: If0bd4934a0bdd824f5ba751096a43e1322aa9f1d
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

tests/baseline/CMakeLists.txt

@@ -0,0 +1,4 @@
+# Special case: test includes the QBaselineTest module sources from qtbase directly
+if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/../../../qtbase/tests/baseline/shared")
+    add_subdirectory(scenegraph)
+endif()