[Feature] add a new response_format is file type when image generate (#1673)

Signed-off-by: rongfu.leng <lenronfu@gmail.com>
Co-authored-by: Gao Han <hgaoaf@connect.ust.hk>

docs/serving/image_generation_api.md

@@ -32,6 +32,20 @@ curl -X POST http://localhost:8000/v1/images/generations \
   }' | jq -r '.data[0].b64_json' | base64 -d > dragon.png
 ```
 
+**Using curl save to file:**
+
+```bash
+curl -o dragon.png -X POST http://localhost:8000/v1/images/generations \
+  -H "Content-Type: application/json" \
+  -d '{
+    "prompt": "a dragon laying over the spine of the Green Mountains of Vermont",
+    "size": "1024x1024",
+    "seed": 42,
+    "response_format":"file"
+  }'
+```
+
+
 **Using Python:**
 
 ```python
@@ -57,6 +71,36 @@ img = Image.open(io.BytesIO(img_bytes))
 img.save("cat.png")
 ```
 
+**Using Python save to file:**
+
+```python
+import requests
+import base64
+from PIL import Image
+import io
+import re
+
+response = requests.post(
+    "http://localhost:8000/v1/images/generations",
+    json={
+        "prompt": "a black and white cat wearing a princess tiara",
+        "size": "1024x1024",
+        "num_inference_steps": 50,
+        "seed": 42,
+        "response_format":"file"
+    }
+)
+
+# save to file
+content_disposition = response.headers.get("Content-Disposition", "")
+match = re.search(r'filename="?(.+)"?', content_disposition)
+filename = match.group(1) if match else "save.png"
+with open(filename, "wb") as f:
+    for chunk in response.iter_content(8192):
+        f.write(chunk)
+print("saved:", filename)
+```
+
 **Using OpenAI SDK:**
 
 ```python