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

[NAKAMURA Takumi via llvm-commits]

chapuni wrote:

I'd like to nominate @evodius96 and @MaskRay , or to let them nominate others.
I know they are busy.

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