[Misc] Introduce encode_*_url utility function (#31208)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

tests/models/multimodal/generation/test_keye.py

@@ -8,7 +8,7 @@ from PIL.Image import Image
 from transformers import AutoProcessor
 
 from vllm import LLM, EngineArgs, SamplingParams
-from vllm.multimodal.utils import encode_image_base64
+from vllm.multimodal.utils import encode_image_url
 
 MODEL_NAME = "Kwai-Keye/Keye-VL-8B-Preview"
 
@@ -31,10 +31,7 @@ def test_keye_vl(
     question: str,
 ):
     images = [asset.pil_image for asset in image_assets]
-
-    image_urls = [
-        f"data:image/jpeg;base64,{encode_image_base64(image)}" for image in images
-    ]
+    image_urls = [encode_image_url(image) for image in images]
 
     engine_args = EngineArgs(
         model=MODEL_NAME,