Initial pass at clang-format config

[andrewfb]

This is my best attempt at creating a clang-format config file that matches Cinder's current formatting. Probably the most egregious difference is that clang-format doesn't provide a mechanism for aligning break statements with case labels llvm/llvm-project#58669.

For Visual Studio users, this file is automatically detected and can be used without any additional configuration when working with the Cinder source code.

I think clang-format is useful enough and has become the accepted standard enough that it's worth modifying Cinder's code style to conform to a clang-format ruleset. However I personally wouldn't want to apply this to the codebase wholesale at this moment because just about every file would be touched to some extent (complicating git blames, among other things), but I'd propose any new code submissions make use of it.