Tune webpack config and add Dockerfile

Add Dockerfile for running containerized dev server. Update webpack
config to make dev server available over exposed docker port.

awx/ui_next/Dockerfile

@@ -0,0 +1,20 @@
+FROM node:10
+ARG NPMRC_FILE=.npmrc
+ENV NPMRC_FILE=${NPMRC_FILE}
+ARG TARGET_HOST='awx'
+ENV TARGET_HOST=${TARGET_HOST}
+ARG TARGET_PORT=8043
+ENV TARGET_PORT=${TARGET_PORT}
+WORKDIR /ui_next
+ADD build build
+ADD dist dist
+ADD images images
+ADD package.json package.json
+ADD package-lock.json package-lock.json
+COPY ${NPMRC_FILE} .npmrc
+RUN npm install
+ADD babel.config.js babel.config.js
+ADD webpack.config.js webpack.config.js
+ADD src src
+EXPOSE 3001
+CMD [ "npm", "run", "start" ]