feat(test): automatically generate test image (#4976)

Signed-off-by: Xu Xingliang <xuxingliang@xiaomi.com>

scripts/LVGLImage.py

@@ -591,6 +591,8 @@ class LVGLImage:
         header = f'''
 #if defined(LV_LVGL_H_INCLUDE_SIMPLE)
 #include "lvgl.h"
+#elif defined(LV_BUILD_TEST)
+#include "../lvgl.h"
 #else
 #include "lvgl/lvgl.h"
 #endif

scripts/install-prerequisites.sh

@@ -6,4 +6,5 @@
 #
 # Note: This script is run by the CI workflows.
 sudo apt update
-sudo apt install gcc python3 libpng-dev ruby-full gcovr cmake libjpeg-turbo8-dev libfreetype6-dev
+sudo apt install gcc python3 libpng-dev ruby-full gcovr cmake libjpeg-turbo8-dev libfreetype6-dev pngquant
+pip3 install pypng lz4