[clang-format] Adds space around braces in text protos

Summary:
This patch modifies the text proto Google style to add spaces around braces.

I investigated using something different than Cpp11BracedListStyle, but it turns out it's what we want and also the java and js styles also depend on that.

Reviewers: djasper

Reviewed By: djasper

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D42685

llvm-svn: 323860