Clang-format: Add Whitesmiths indentation style

Summary:
This patch adds support for the Whitesmiths indentation style to clang-format. It’s an update to a patch submitted in 2015 (D6833), but reworks it to use the newer API.

There are still some issues with this patch, primarily around `switch` and `case` support. The added unit test won’t currently pass because of the remaining issues.

Reviewers: mboehme, MyDeveloperDay, djasper

Reviewed By: MyDeveloperDay

Subscribers: krasimir, MyDeveloperDay, echristo, cfe-commits

Patch By: @timwoj (Tim Wojtulewicz)

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67627

llvm-svn: 372497