feat(docker): reduce the size of alpine docker images (#3973)

* reduce redundant code between the two alpine Dockerfiles
* reduce the docker image build times
* reduce the `n8n` image size from 1.17GB to 462MB
* reduce the `n8n-custom` image size from 671MB to 460MB
* reduce the size of npm tree by making all typing packages devDependencies

Partially resolves this ticket: N8N-3252

.github/workflows/docker-base-image.yml

@@ -0,0 +1,35 @@
+name: Docker Base Image CI
+
+on:
+  workflow_dispatch:
+    inputs:
+      node_version:
+        description: 'Node.js version to build this image with.'
+        type: string
+        required: true
+        default: '16'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+      - name: Build
+        uses: docker/build-push-action@v2
+        with:
+          context: ./docker/images/n8n-base
+          build-args: |
+            NODE_VERSION=${{github.event.inputs.node_version}}
+          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          push: true
+          tags: |
+            ${{ secrets.DOCKER_USERNAME }}/base:${{ github.event.inputs.node_version }}

.github/workflows/docker-images-nightly.yml

@@ -57,7 +57,7 @@ jobs:
           file: ./docker/images/n8n-custom/Dockerfile
           platforms: linux/amd64
           push: true
-          tags: n8nio/n8n:${{ github.event.inputs.tag || 'nightly' }}
+          tags: ${{ secrets.DOCKER_USERNAME }}/n8n:${{ github.event.inputs.tag || 'nightly' }}
           no-cache: true
       - name: Call Success URL - optionally
         run: |