add configuration to use react-express-mysql sample with Docker Dev Environments feature (#270)

Signed-off-by: Guillaume Lours <guillaume.lours@docker.com>

react-express-mysql/frontend/Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker/dockerfile:1.4
+
 FROM node:lts AS development
 
 ENV CI=true
@@ -15,6 +17,21 @@ FROM development AS builder
 
 RUN npm run build
 
+FROM development as dev-envs
+RUN <<EOF
+apt-get update
+apt-get install -y --no-install-recommends git
+EOF
+
+RUN <<EOF
+useradd -s /bin/bash -m vscode
+groupadd docker
+usermod -aG docker vscode
+EOF
+# install Docker tools (cli, buildx, compose)
+COPY --from=gloursdocker/docker / /
+CMD [ "npm", "start" ]
+
 FROM nginx:1.13-alpine
 
 COPY --from=builder /code/build /usr/share/nginx/html