github: Add clang-format action

.github/workflows/clang-format.yml

@@ -0,0 +1,18 @@
+name: clang-format
+
+on: [push, pull_request]
+
+jobs:
+  clang-format:
+
+    runs-on: ubuntu-latest
+
+    steps:
+
+    - name: Checkout dynarmic repo
+      uses: actions/checkout@v2
+
+    - uses: DoozyX/clang-format-lint-action@v0.12
+      with:
+        source: 'src tests'
+        clangFormatVersion: 12