feat(draw): add initial SDL renderer

It caches SW rendered bitmaps in textures.
The cache is also updated to support data and source separately.
E.g. source is a path to an image, and if that image changes all
related cache entries needs to found and invalidated.

Limitations of SDL rederer:
- not all draw task types are supported
- image transformation is not supported
- some textures (e.g. button matrix texts) are not detected as cached
- images are not cached
- images are supported only from path

demos/vector_graphic/lv_demo_vector_graphic.c

@@ -225,7 +225,7 @@ static void draw_vector(lv_layer_t * layer)
 
 void lv_demo_vector_graphic(void)
 {
-    static uint8_t canvas_buf[WIDTH * HEIGHT * 4];
+    static uint8_t canvas_buf[LV_CANVAS_BUF_SIZE(WIDTH, HEIGHT, 32, LV_DRAW_BUF_STRIDE_ALIGN)];
 
     lv_obj_t * canvas = lv_canvas_create(lv_scr_act());
     lv_canvas_set_buffer(canvas, canvas_buf, WIDTH, HEIGHT, LV_COLOR_FORMAT_ARGB8888);