[clang-tools-extra] [Clang-Tidy] Fixed `cppcoreguidelines-init-variables` to handle ObjC for-in loops. (PR #191306)

[Victor Chernyakin via cfe-commits]

localspook wrote:

"No uninitialized variables" seems like a reasonable rule to want to enforce even in Objective-C++, so I don't think this particular check should be disabled there. Maybe some individual cppcoreguidelines checks wouldn't apply, but I think we should decide on a check-by-check basis.

https://github.com/llvm/llvm-project/pull/191306