Adds a custom action to check the target branch (#9046)

* ci: added cerebrus action to validate files in PRs based on the target branch

* fix: reflect move of action repo to TW org

* use cerebrus v2

* fix: use pull_request_target to enable write access

.github/workflows/pr-path-validation.yml

@@ -0,0 +1,18 @@
+name: Validate PR Paths
+
+on:
+  pull_request_target:
+    types: [opened, reopened, synchronize]
+
+jobs:
+  validate-pr:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Validate PR
+      uses: TiddlyWiki/cerebrus@v2
+      with:
+        pr_number: ${{ github.event.pull_request.number }}
+        repo: ${{ github.repository }}
+        base_ref: ${{ github.base_ref }}
+        github_token: ${{ secrets.GITHUB_TOKEN }}