arch add small 3rd party libs to lvgl (#2569)

* move png, sjpg, bmp, gif, fs_if to extra/libs

* reorganize the examples

* update lv_conf_internal.h

* fix warnings

* add freetype

* remove unused assets

* add the new libs to build tests

* update the docs

examples/libs/bmp/lv_example_bmp.h

@@ -0,0 +1,38 @@
+/**
+ * @file lv_example_bmp.h
+ *
+ */
+
+#ifndef LV_EXAMPLE_BMP_H
+#define LV_EXAMPLE_BMP_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*********************
+ *      INCLUDES
+ *********************/
+
+/*********************
+ *      DEFINES
+ *********************/
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+
+/**********************
+ * GLOBAL PROTOTYPES
+ **********************/
+void lv_example_bmp_1(void);
+
+/**********************
+ *      MACROS
+ **********************/
+
+#ifdef __cplusplus
+} /*extern "C"*/
+#endif
+
+#endif /*LV_EXAMPLE_BMP_H*/