ci: build OPCUA image in CI.

This workflow will only run for tags for now, since otherwise it would
have to deal with relying on a ${tag}-dev container for the base image.

If we add more included images, we can add a matrix to the workflow
definition to build all their images.

This commit was based on [1].

[1] https://stackoverflow.com/questions/58457140

.github/workflows/included-images.yml

@@ -0,0 +1,33 @@
+name: Build included image
+on:
+  workflow_run:
+    workflows: ["Base image build"]
+    tags:
+      - 'v*'
+    types:
+      - completed
+
+jobs:
+  build_and_push:
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+      contents: read
+    env:
+      REGISTRY: ghcr.io/${{ github.repository_owner }}
+      TAG: ${{ github.ref_name }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: docker/setup-buildx-action@v3
+      - name: Log in to registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Build and push tagged image
+        uses: docker/bake-action@v4
+        with:
+          workdir: images/
+          files: docker-compose-opcua.yml
+          push: true