let's check the format via some github action

Signed-off-by: Matthieu Gallien <matthieu.gallien@nextcloud.com>

.github/workflows/clang-format.yml

@@ -0,0 +1,15 @@
+name: Clang Format Checker
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - uses: DoozyX/clang-format-lint-action@v0.14
+      with:
+        source: '.'
+        extensions: 'h,cpp,c'
+        clangFormatVersion: 14