check crosslink and go mod tidy in CI

.github/workflows/module-check.yaml

@@ -0,0 +1,22 @@
+name: Check modules
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Install Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: "~1.20.2"
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          submodules: true
+      - name: Generate
+        run: make crosslink go-mod-tidy
+      - name: Check Clean Work Tree
+        run: make check-clean-work-tree