feat: implement ESRGAN upscaler + Metal Backend (#104)

* add esrgan upscaler

* add sd_tiling

* support metal backend

* add clip_skip

---------

Co-authored-by: leejet <leejet714@gmail.com>

stable-diffusion.h

@@ -4,6 +4,7 @@
 #include <memory>
 #include <string>
 #include <vector>
+#include "ggml/ggml.h"
 
 #include "ggml/ggml.h"
 
@@ -41,14 +42,17 @@ public:
     StableDiffusion(int n_threads                = -1,
                     bool vae_decode_only         = false,
                     std::string taesd_path       = "",
+                    std::string esrgan_path      = "",
                     bool free_params_immediately = false,
+                    bool vae_tiling              = false,
                     std::string lora_model_dir   = "",
                     RNGType rng_type             = STD_DEFAULT_RNG);
 
     bool load_from_file(const std::string& model_path,
                         const std::string& vae_path,
                         ggml_type wtype,
-                        Schedule d = DEFAULT);
+                        Schedule d = DEFAULT,
+                        int clip_skip = -1);
 
     std::vector<uint8_t*> txt2img(
         std::string prompt,