ci: Add Clang Format Github Action

Reference:
https://github.com/RafikFarhad/clang-format-github-action
https://stackoverflow.com/questions/33258159/how-to-make-clang-format-skip-sections-of-c-code

.github/workflows/clang-format.yml

@@ -0,0 +1,16 @@
+name: Clang Format
+
+on:
+  push:
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  clang-format-checking:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: RafikFarhad/clang-format-github-action@v1.0.1
+        with:
+          sources: "src/**/*.h,src/**/*.cpp"
+          style: file

src/perfect/perfectAI.cpp

@@ -9,6 +9,7 @@
 #include "perfectAI.h"
 #include <cassert>
 
+// clang-format off
 unsigned int soTableTurnLeft[] = {
  2,      14,      23,
     5,   13,   20,
@@ -168,6 +169,7 @@ unsigned int soTableMirrorDiag2[] = {
      18,   10,    3,
   21,       9,       0
 };
+// clang-format on
 
 // define the four groups
 unsigned int squareIndexGroupA[] = { 3, 5, 20, 18 };