Add incremental dockerfiles

04-building-container-images/sample-app/client-react/Dockerfile.3

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+FROM node:19.4-bullseye AS build
+
+# Specify working directory other than /
+WORKDIR /usr/src/app
+
+# Copy only files required to install
+# dependencies (better layer caching)
+COPY package*.json ./
+
+# Use cache mount to speed up install of existing dependencies
+RUN --mount=type=cache,target=/usr/src/app/.npm \
+  npm set cache /usr/src/app/.npm && \
+  npm install
+
+COPY . .
+
+RUN npm run build
+
+# Use separate stage for deployable image
+FROM nginx:1.23-alpine
+
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+
+COPY --from=build usr/src/app/dist/ /usr/share/nginx/html