Update Prettier scripts and supported files (#402)

.github/workflows/lint.yml

@@ -0,0 +1,22 @@
+name: Node CI
+
+on: [push]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v1
+
+      - name: Setup Node.js 12.x
+        uses: actions/setup-node@v1
+        with:
+          node-version: 12.x
+
+      - name: Install and lint
+        run: |
+          npm ci
+          npm run test:code
+        env:
+          CI: true