feat: support use docker image to build cpp wasmplugin at local

plugins/wasm-cpp/Dockerfile

@@ -0,0 +1,16 @@
+ARG BUILDER=higress-registry.cn-hangzhou.cr.aliyuncs.com/higress/build-tools-proxy:release-1.12-2021-12-09T23-01-43
+FROM $BUILDER as builder
+
+ARG PLUGIN_NAME
+
+WORKDIR /workspace
+
+COPY . .
+
+RUN bazel build //extensions/$PLUGIN_NAME:$PLUGIN_NAME.wasm
+
+FROM scratch as output
+
+ARG PLUGIN_NAME
+
+COPY --from=builder /workspace/bazel-bin/extensions/$PLUGIN_NAME/$PLUGIN_NAME.wasm plugin.wasm

plugins/wasm-cpp/Makefile

@@ -0,0 +1,14 @@
+PLUGIN_NAME ?= key_auth
+BUILD_TIME := $(shell date "+%Y%m%d-%H%M%S")
+COMMIT_ID := $(shell git rev-parse --short HEAD 2>/dev/null)
+IMAGE_TAG = $(if $(strip $(PLUGIN_VERSION)),${PLUGIN_VERSION},${BUILD_TIME}-${COMMIT_ID})
+IMG ?= ${REGISTRY}${PLUGIN_NAME}:${IMAGE_TAG}
+
+.PHONY: build
+build:
+	DOCKER_BUILDKIT=1 docker build --build-arg PLUGIN_NAME=${PLUGIN_NAME} \
+	                            -t ${IMG} \
+	                            --output extensions/${PLUGIN_NAME} \
+	                            .
+	@echo ""
+	@echo "output wasm file: extensions/${PLUGIN_NAME}/plugin.wasm"