[clang] [Format] Configure ASSIGN_OR_RETURN macros for Google style (PR #169037)

[Björn Schäpers via cfe-commits]

HazardyKnusperkeks wrote:

Can you link to some documentation for these macros? And maybe adapt the commit message. If you want to attribute it to a different person, commit in their name. (`git commit --author="Foo bar <foo at bar.com>"`)

https://github.com/llvm/llvm-project/pull/169037