Add wrapper-validation workflow

Although we run `setup-gradle` with all/most wrapper files, this global
workflow will ensure that all wrapper files in the repo are valid.
(This should help with the OSSF scorecard)

.github/workflows/ci-validate-wrappers.yml

@@ -0,0 +1,14 @@
+name: CI-validate-wrappers
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  validation:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: gradle/actions/wrapper-validation@v4
+        with:
+          allow-checksums: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855