Add CodeSQL actions workflow

.github/workflows/codeql.yml

@@ -0,0 +1,24 @@
+name: "CodeQL analysis"
+
+on: 
+  push:
+  schedule:
+    - cron: '0 0 * * 0'
+
+jobs:
+  codeql:
+
+    strategy:
+      fail-fast: false
+
+    runs-on: ubuntu-latest # windows-latest and ubuntu-latest are supported. macos-latest is not supported at this time. 
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+        
+    - name: Initialize CodeQL 
+      uses: github/codeql-action/init@v1
+    
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v1