Optimize G-code / feature dependencies (#18919)

Marlin/src/feature/caselight.h

@@ -21,9 +21,25 @@
  */
 #pragma once
 
-extern uint8_t case_light_brightness;
-extern bool case_light_on;
-extern uint8_t case_light_brightness_sav;   // saves brighness info when case_light_on is false
-extern bool case_light_arg_flag;  // flag to notify if S or P argument type
+#include "../inc/MarlinConfigPre.h"
 
-void update_case_light();
+#if ENABLED(CASE_LIGHT_USE_NEOPIXEL)
+  #include "leds/leds.h"
+#endif
+
+class CaseLight {
+public:
+  static uint8_t brightness;
+  static bool on;
+
+  static void update(const bool sflag);
+  static inline void update_brightness() { update(false); }
+  static inline void update_enabled() { update(true); }
+
+private:
+  #if ENABLED(CASE_LIGHT_USE_NEOPIXEL)
+    static LEDColor color;
+  #endif
+};
+
+extern CaseLight caselight;