[GitHub Actions] Change Auto-Label Trigger (#228)

- The execution of applying labels is now in a dispatched workflow that executes from the default branch and has access to the GitHub App to be able to write labels.
- New GitHub Actions to enable/toggle workflows from activating during import of subprojects.
- Workflows to add new subtrees to develop and release branches.

.github/workflows/initial-setup.yml

@@ -11,6 +11,19 @@ jobs:
   setup-super-repo:
     runs-on: ubuntu-24.04
     steps:
+      - name: Validate maintainer permissions
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          echo "Actor is: ${{ github.actor }}"
+          PERMISSION=$(gh api \
+            repos/${{ github.repository }}/collaborators/${{ github.actor }}/permission \
+            --jq .permission)
+          if [[ "$PERMISSION" != "admin" && "$PERMISSION" != "maintain" ]]; then
+            echo "❌ User ${{ github.actor }} is not authorized to run this workflow"
+            exit 1
+          fi
+
       - name: Generate a token
         id: generate-token
         uses: actions/create-github-app-token@df432ceedc7162793a195dd1713ff69aefc7379e # v2.0.6