[backport 1.27] [ci] add JSON validation CI workflow (#5838)

Backport of #5837 to `core/1.27`

Automatically created by backport workflow.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5838-backport-1-27-ci-add-JSON-validation-CI-workflow-27c6d73d36508113a05fcd1a5bfc6512)
by [Unito](https://www.unito.io)

Co-authored-by: Christian Byrne <cbyrne@comfy.org>

.github/workflows/json-validate.yaml

@@ -0,0 +1,15 @@
+name: Validate JSON
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  json-lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Validate JSON syntax
+        run: ./scripts/cicd/check-json.sh