[clang-format] [PR36858] Add missing .hh and .cs extensions from python support utilities

Summary: https://bugs.llvm.org/show_bug.cgi?id=36858 identifies .hh as a missing C++ header extension file while making this change I realized there was no support for .cs files which were added recently

Reviewers: pseyfert, klimek, owenpan

Reviewed By: klimek

Subscribers: cfe-commits

Tags: #clang-tools-extra, #clang

Differential Revision: https://reviews.llvm.org/D67949

llvm-svn: 372760