chore(ci): add style check workflow (#58)

* chore(ci): add style check workflow

* chore(ci/style): show helpful error message on failure

Author: glennsl

.github/workflows/style.yml

@@ -0,0 +1,23 @@
+name: Style Check
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Use Node.js 19
+        uses: actions/setup-node@v3
+        with:
+          node-version: 19
+      - run: npm install
+      - run: npx rescript format -all -check
+      - name: Helpful error message
+        if: failure()
+        run: echo "::error::Incorrect formatting. Please run 'npx rescript format -all' and commit the changes."