ci: add GitHub Workflow for building container-images

Test building container images, so that Mergify can require
`build_controller` and `build_sidecar` as CI jobs.

Signed-off-by: Niels de Vos <ndevos@redhat.com>

Author: nixpanic

.github/workflows/test-build.yaml

@@ -0,0 +1,52 @@
+---
+name: Test building container images
+
+on:
+  pull_request:
+    branches:
+      - "*"
+
+jobs:
+  build_controller:
+    name: Build controller container image
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v2
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Build container container image
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          file: Dockerfile
+          platforms: linux/amd64,linux/arm64,linux/ppc64le,linux/s390x,linux/arm/v7
+          push: false
+          tags: quay.io/csi-addons/k8s-controller:latest
+
+  build_sidecar:
+    name: Test sidecar container image
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v2
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Build sidecar container image
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          file: build/Containerfile.sidecar
+          platforms: linux/amd64,linux/arm64,linux/ppc64le,linux/s390x,linux/arm/v7
+          push: false
+          tags: quay.io/csi-addons/k8s-sidecar:latest