Added new github action to find compile errors on commits to main

.github/workflows/test-docker-build.yml

@@ -0,0 +1,22 @@
+name: Test Build
+
+on:
+    push:
+        branches:
+            - main
+    pull_request:
+        types:
+            - closed
+        branches:
+            - main
+
+jobs:
+    build:
+        runs-on: ubuntu-latest
+
+        steps:
+            - name: Checkout code
+              uses: actions/checkout@v2
+
+      - name: Build Docker image
+        run: docker build -t moonlightpanel/moonlight:${{ github.sha }} -f Moonlight/Dockerfile .