[clang] [clang-format] Support of TableGen formatting. (PR #76059)

[Hirofumi Nakamura via cfe-commits]

hnakamura5 wrote:

Thanks to the advises, I begin to split this into several parts.

Made the keywords part in https://github.com/llvm/llvm-project/pull/77477 .

https://github.com/llvm/llvm-project/pull/76059