[clang-tools-extra] Rename CODE_OWNERS -> Maintainers (PR #114544)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

I've kept everyone in the same position they were previously in, just reworded for the newer nomenclature.

That said, I'd like explicit confirmation from @r4nt @njames93 and @sam-mccall that they're still willing and able to volunteer under the new maintainers guidance (https://llvm.org/docs/DeveloperPolicy.html#maintainers) before landing these changes. If you're not able to do so, that's totally fine! I can move you to the inactive maintainers part of the list and we can try to find other volunteers to step in to the role.

Also, I cannot seem to find a GitHub handle for Julie Hockett and her last community interactions seem to be from 2021. If someone can help find the correct information and tag her on the review, that would be appreciated.

https://github.com/llvm/llvm-project/pull/114544