[llvm] [LLVM][Maintainers] Add llvm-cov / Coverage maintainer (PR #130590)

[NAKAMURA Takumi via llvm-commits]

https://github.com/chapuni approved this pull request.

Sorry for the delay. I can accept. Thanks for the nomination.

That said, I am still a reviewee with bunch of unapproved request. I'd really like more a few maintainers in this area.

https://github.com/llvm/llvm-project/pull/130590