Extract container registry credentials to workflow inputs

.github/workflows/check-submission.yml

@@ -28,6 +28,18 @@ on:
         required: false
         default: ghcr.io
 
+      container-registry-username:
+        description: Username to container registry
+        type: string
+        required: false
+        default: ${{ github.actor }}
+
+      container-registry-password:
+        description: Password to container registry
+        type: string
+        required: false
+        default: ${{ secrets.GITHUB_TOKEN }}
+
       binder-cache-branch:
         description: If set (default), the built container image will be written to .binder/Dockerfile and pushed to this branch. To disable this, set it to the empty string.
         type: string
@@ -152,8 +164,8 @@ jobs:
         with:
           NO_PUSH: "false"
           DOCKER_REGISTRY: ${{ inputs.container-registry }}
-          DOCKER_USERNAME: ${{ github.actor }}
-          DOCKER_PASSWORD: ${{ secrets.GITHUB_TOKEN }}
+          DOCKER_USERNAME: ${{ inputs.container-registry-username }}
+          DOCKER_PASSWORD: ${{ inputs.container-registry-password }}
           IMAGE_NAME: ${{ env.NORMALIZED_IMAGE_NAME }}
           MYBINDERORG_TAG: ${{ github.sha }}
 
@@ -167,9 +179,9 @@ jobs:
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3
         with:
-          registry: ghcr.io
-          username: ${{ github.actor }}
-          password: ${{ secrets.GITHUB_TOKEN }}
+          registry: ${{ inputs.container-registry }}
+          username: ${{ inputs.container-registry-username }}
+          password: ${{ inputs.container-registry-password }}
 
       - name: Run command to test built image ${{ needs.image-build.outputs.image }}
         id: run