[clang-tools-extra] [clang-tidy] performance-unnecessary-copy-init: Add a hook... (PR #73921)

[Clement Courbet via cfe-commits]

legrosbuffle wrote:

> In theory changes that are required for "private" checks should be done by you on some own private fork instead of adding that "unused" code here. But only option I see is simply moving diagnostic to separate methods, and make those methods virtual. 

I see, we don't want code that's dead upstream. Makes sense. I'll do something like what you're suggesting.

https://github.com/llvm/llvm-project/pull/73921