clang-format all the things

[zeke]

We recommend using clang-format for linting C/C++/Objective-C code. Rather than burying this recommendation in a doc somewhere, perhaps we should enforce this style.

A rough outline of how this could go down:

1. clang-format all the existing code
2. add clang-format as part of the existing lint-cpp task
3. Add a clang-format pre-commmit git hook using husky
4. Update or remove docs/development/clang-format.md

Considerations:

@ckerr:

The thing to avoid is having patches that intermix formatting changes and code changes, because that makes things hairy when you need to go back through the log looking for something in the diffs. So the best you can do is have a flag day patch that reformats everything and then turn clang-format into the linter at the same time

@codebytere:

my initial opinion would be to think about integrating it around the same time we attempt to integrate linting for objc code

[zeke]

Excellent work, @codebytere! 🙌