Ability to push ARM/AMD64 Operator UI images to GHCR (#2426)

* Updated to build for UI and push to GHCR
* Enable build for both Operator and Operator UI

.github/workflows/publish_ghcr_image.yaml

@@ -3,6 +3,7 @@ name: Publish multiarch postgres-operator image on ghcr.io
 env:
   REGISTRY: ghcr.io
   IMAGE_NAME: ${{ github.repository }}
+  IMAGE_NAME_UI: ${{ github.repository }}-ui
 
 on:
   push:
@@ -30,7 +31,13 @@ jobs:
         id: image
         run: |
             IMAGE="${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${GITHUB_REF/refs\/tags\//}"
-            echo "NAME=$IMAGE" >> $GITHUB_OUTPUT
+            echo "NAME=${IMAGE,,}" >> $GITHUB_OUTPUT
+
+      - name: Define image name
+        id: image_ui
+        run: |
+            IMAGE="${{ env.REGISTRY }}/${{ env.IMAGE_NAME_UI }}:${GITHUB_REF/refs\/tags\//}"
+            echo "NAME=${IMAGE,,}" >> $GITHUB_OUTPUT
 
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v2
@@ -54,3 +61,14 @@ jobs:
           build-args: BASE_IMAGE=alpine:3.15
           tags: "${{ steps.image.outputs.NAME }}"
           platforms: linux/amd64,linux/arm64
+
+      - name: Build and push multiarch image to ghcr for UI
+        uses: docker/build-push-action@v3
+        with:
+          context: ${{ github.workspace }}/ui
+          file: ${{ github.workspace }}/ui/Dockerfile
+          push: true
+          build-args: BASE_IMAGE=alpine:3.15
+          tags: "${{ steps.image_ui.outputs.NAME }}"
+          platforms: linux/amd64,linux/arm64
+