feat: allow use local branch to build image (#9546)

docker/Dockerfile

 ARG CUDA_VERSION=12.6.1
-FROM nvidia/cuda:${CUDA_VERSION}-cudnn-devel-ubuntu22.04
+FROM nvidia/cuda:${CUDA_VERSION}-cudnn-devel-ubuntu22.04 as base
 
 ARG BUILD_TYPE=all
+ARG BRANCH_TYPE=remote
 ARG DEEPEP_COMMIT=b92d0d4860ce6866cd6d31bfbae937f9a7a3772b
 ARG CMAKE_BUILD_PARALLEL_LEVEL=2
 ENV DEBIAN_FRONTEND=noninteractive \
@@ -58,10 +59,21 @@ RUN mkdir -p /tmp/gdrcopy && cd /tmp \
 # Fix DeepEP IBGDA symlink
 RUN ln -sf /usr/lib/x86_64-linux-gnu/libmlx5.so.1 /usr/lib/x86_64-linux-gnu/libmlx5.so
 
-# Clone and install SGLang
+FROM scratch AS local_src
+COPY . /src
+
+FROM base AS build-image
+# Install SGLang
 WORKDIR /sgl-workspace
+ARG BRANCH_TYPE
+COPY --from=local_src /src /tmp/local_src
+RUN if [ "$BRANCH_TYPE" = "local" ]; then \
+        cp -r /tmp/local_src /sgl-workspace/sglang; \
+    else \
+        git clone --depth=1 https://github.com/sgl-project/sglang.git /sgl-workspace/sglang; \
+    fi \
+ && rm -rf /tmp/local_src
 RUN python3 -m pip install --no-cache-dir --upgrade pip setuptools wheel html5lib six \
- && git clone --depth=1 https://github.com/sgl-project/sglang.git \
  && cd sglang \
  && case "$CUDA_VERSION" in \
       12.6.1) CUINDEX=126 ;; \