feat: update the cmsis-pack to 0.8.3 (#3021)

* doc: add readme.md for cmsis-pack

* feat: add benchmark to cmsis-pack

* fix: force WORD alignment for enabling AC6 auto-vectorization

* feat: add demo:widgets

* fix: use the original lv_demos.h

demos/lv_demos.h

@@ -15,11 +15,25 @@ extern "C" {
  *********************/
 #include "../lvgl.h"
 
-#include "widgets/lv_demo_widgets.h"
-#include "benchmark/lv_demo_benchmark.h"
-#include "stress/lv_demo_stress.h"
-#include "keypad_encoder/lv_demo_keypad_encoder.h"
-#include "music/lv_demo_music.h"
+#if LV_USE_DEMO_WIDGETS
+    #include "widgets/lv_demo_widgets.h"
+#endif
+
+#if LV_USE_DEMO_BENCHMARK
+    #include "benchmark/lv_demo_benchmark.h"
+#endif
+
+#if LV_USE_DEMO_STRESS
+    #include "stress/lv_demo_stress.h"
+#endif
+
+#if LV_USE_DEMO_KEYPAD_AND_ENCODER
+    #include "keypad_encoder/lv_demo_keypad_encoder.h"
+#endif
+
+#if LV_USE_DEMO_MUSIC
+    #include "music/lv_demo_music.h"
+#endif
 
 /*********************
  *      DEFINES