Move tmk_core/common/backlight to quantum/backlight (#6710)

* Move tmk_core/common/backlight to quantum/backlight

* Add guards to backlight inclusion

* Add guards to backlight inclusion

* Update backlight guards on clueboard/60

* Use full paths to avoid vpath issues

quantum/keymap_common.c

@@ -26,9 +26,12 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "action.h"
 #include "action_macro.h"
 #include "debug.h"
-#include "backlight.h"
 #include "quantum.h"
 
+#ifdef BACKLIGHT_ENABLE
+#    include "backlight.h"
+#endif
+
 #ifdef MIDI_ENABLE
 #    include "process_midi.h"
 #endif