Add serverless operator build push

.github/workflows/serverless-operator-build-push.yaml

@@ -0,0 +1,41 @@
+name: serverless operator build (pull)
+
+on:
+  pull_request_target:
+    types: [opened, edited, synchronize, reopened, ready_for_review]
+
+permissions:
+  id-token: write
+  contents: read
+
+jobs:
+  compute-tag:
+    runs-on: ubuntu-latest
+    outputs:
+      tag: ${{ steps.get_tag.outputs.TAG }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Get the latest tag
+        id: get_tag
+        run: echo ::set-output name=TAG::PR-${{ github.event.pull_request.number }}
+
+      - name: Echo the tag
+        run: echo ${{ steps.get_tag.outputs.TAG }}
+
+  build-image:
+    needs: compute-tag
+    uses: kyma-project/test-infra/.github/workflows/image-builder.yml@main
+    with:
+      name: serverless-operator/ga
+      dockerfile: components/operator/Dockerfile
+      context: .
+      tags: ${{ needs.compute-tag.outputs.tag }}
+
+  test-image:
+    runs-on: ubuntu-latest
+    needs: build-image
+    steps:
+      - name: Test image
+        run: echo "Testing image ${{ needs.build-image.outputs.images }}"