cli/worker/tests: facade-only linkage and updated test suites

oak-cli and oak-render-worker use the C ABI exclusively (0 olive::
symbols). Google Test suites updated for the migrated APIs, new engine
facade test coverage, CLI transcode verification.

tests/gtest/render_processor_test.cpp

@@ -41,7 +41,7 @@
 #include "node/globals.h"
 #include "node/project.h"
 #include "render/job/acceleratedjob.h"
-#include "render/managedcolor.h"
+#include "widget/manageddisplay/colorprocessorhandle.h"
 #include "render/renderjobtracker.h"
 #include "render/rendermanager.h"
 #include "render/renderprocessor.h"