Rework Dockerfile to build the frontend

which removes the commited build files from the repo

Dockerfile

@@ -0,0 +1,41 @@
+FROM alpine:3.12 as frontend
+
+RUN apk add --no-cache \
+  npm
+
+WORKDIR /build
+COPY [ "package.json", "package-lock.json", "/build/" ]
+RUN npm install
+
+COPY [ "angular.json", "tsconfig.json", "/build/" ]
+COPY [ "src/", "/build/src/" ]
+RUN npm run ng build --prod
+
+#--------------#
+
+FROM alpine:3.12
+
+ENV UID=1000 \
+  GID=1000 \
+  USER=youtube
+
+RUN addgroup -S $USER -g $GID && adduser -D -S $USER -G $USER -u $UID
+
+RUN apk add --no-cache \
+  ffmpeg \
+  npm \
+  python2 \
+  su-exec \
+  && apk add --no-cache --repository http://dl-cdn.alpinelinux.org/alpine/edge/testing/ \
+    atomicparsley
+
+WORKDIR /app
+COPY --chown=$UID:$GID [ "backend/package.json", "backend/package-lock.json", "/app/" ]
+RUN npm install && chown -R $UID:$GID ./
+
+COPY --chown=$UID:$GID --from=frontend [ "/build/backend/public/", "/app/public/" ]
+COPY --chown=$UID:$GID [ "/backend/", "/app/" ]
+
+EXPOSE 17442
+ENTRYPOINT [ "/app/entrypoint.sh" ]
+CMD [ "node", "app.js" ]