Add CI to validate protos version on cap-dev branch (#217)

* Added CI validation to ensure protos submodule points to cap-dev branch

* Updated checkout action version

* Moved validate-submodule CI to its own workflow

* Moved permissions to job

* Updated checkout action version

Author: amit-momin

.github/workflows/validate-submodule.yml

@@ -0,0 +1,44 @@
+name: Validate Submodule
+permissions: {}
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+    branches: [capabilities-development]
+  push:
+    branches: [capabilities-development]
+
+jobs:
+  validate-submodule:
+    permissions:
+      contents: read
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+        with:
+          submodules: recursive
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Validate chainlink-protos points to capabilities-development
+        run: |
+          cd submodules/chainlink-protos
+          SUBMODULE_COMMIT=$(git rev-parse HEAD)
+          echo "Submodule commit: $SUBMODULE_COMMIT"
+
+          if [ "$(git rev-parse --is-shallow-repository)" = "true" ]; then
+            echo "Shallow clone detected, fetching full history..."
+            git fetch --unshallow origin
+          fi
+          git fetch origin capabilities-development
+
+          BRANCH_TIP=$(git rev-parse FETCH_HEAD)
+          echo "capabilities-development tip: $BRANCH_TIP"
+
+          if git merge-base --is-ancestor "$SUBMODULE_COMMIT" "$BRANCH_TIP"; then
+            echo "OK: Submodule commit $SUBMODULE_COMMIT is on the capabilities-development branch."
+          else
+            echo "::error::chainlink-protos submodule is at commit $SUBMODULE_COMMIT which is NOT on the capabilities-development branch."
+            echo "Update the submodule to point to a commit from the capabilities-development branch."
+            exit 1
+          fi