feat: add configurable reference image processing for edit models (#1780)

include/stable-diffusion.h

@@ -363,8 +363,7 @@ typedef struct {
     sd_image_t init_image;
     sd_image_t* ref_images;
     int ref_images_count;
-    bool auto_resize_ref_image;
-    bool increase_ref_index;
+    const char* ref_image_args;
     sd_image_t mask_image;
     int width;
     int height;