FrontendCommon: Add option to inhibit screensaver

src/frontend-common/inhibit_screensaver.h

@@ -0,0 +1,7 @@
+#include "common/window_info.h"
+
+namespace FrontendCommon
+{
+void SuspendScreensaver(const WindowInfo& wi);
+void ResumeScreensaver();
+}