Add automated security scanning to our repo (#4166)

.github/workflows/codeql-analysis.yml

@@ -0,0 +1,33 @@
+
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ master ]
+  schedule:
+    - cron: '28 21 * * 3'
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v1
+      with:
+        languages: javascript
+
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v1
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v1