chore(build): add workflow for building images (#9)

Author: sachk

.github/workflows/docker.yml

@@ -0,0 +1,42 @@
+name: Docker
+on:
+  push:
+    branches: [ "master" ]
+
+jobs:
+  build:
+    name: "Build (${{ matrix.component }})"
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    strategy:
+      fail-fast: false
+      matrix:
+        component: [frontend, backend]
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+        with:
+          platforms: arm64
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      - name: Log into registry ${{ env.REGISTRY }}
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GH_TOKEN }}
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v3
+        with:
+          context: ${{ matrix.component }}
+          push: ${{ github.event_name != 'pull_request' }}
+          platforms: linux/amd64
+          file: ${{ matrix.component }}/Dockerfile
+          tags: |
+            ghcr.io/csesoc/subcomp-${{ matrix.component }}:${{ github.sha }}
+            ghcr.io/csesoc/subcomp-${{ matrix.component }}:latest
+          labels: ${{ steps.meta.outputs.labels }}