Request for .clang-format~

Hi,

The docs says that the DGL generally follows the Google C++ style guide, but the code seems different from it. Could the team push .clang-format on GitHub to unify the style~

{ BasedOnStyle: Google, IndentWidth: 2, ContinuationIndentWidth: 2 }

thx, I have tried this config in CLion. But when I format the code, there are still two many changes, which makes it difficult to look for what I’ve written. I mean, there are many files don’t fit with your config. :face_with_thermometer: