ci: build grpc kbs every merge to main

Now we only build kbs-built-in-coco-as every merging to main. We also
need kbs-grpc-coco-as. In this way we can test whether the current KBS
cluster (kbs-grpc-coco-as, coco-as, rvps and coco-keyprovider) works
well together.

Signed-off-by: Xynnn007 <[email protected]>

.github/workflows/kbs-build-and-push.yaml

@@ -23,8 +23,12 @@ jobs:
         username: ${{ github.actor }}
         password: ${{ secrets.GITHUB_TOKEN }}
 
-    - name: Build Container Image
+    - name: Build Container Image KBS (built-in AS)
       run: |
         commit_sha=${{ github.sha }}
         DOCKER_BUILDKIT=1 docker build -t ghcr.io/confidential-containers/staged-images/kbs:${commit_sha} -t ghcr.io/confidential-containers/staged-images/kbs:latest --build-arg KBS_FEATURES=coco-as-builtin,openssl,resource,opa . -f kbs/docker/Dockerfile --push
 
+    - name: Build Container Image KBS (gRPC AS)
+      run: |
+        commit_sha=${{ github.sha }}
+        DOCKER_BUILDKIT=1 docker build -t ghcr.io/confidential-containers/staged-images/kbs-grpc-as:${commit_sha} -t ghcr.io/confidential-containers/staged-images/kbs-grpc-as:latest . -f kbs/docker/Dockerfile.coco-as-grpc --push