[clang-tools-extra] [llvm] [clang-tidy] Prototype: removing the `IncludeStyle` option (PR #185879)

[Victor Chernyakin via cfe-commits]

localspook wrote:

So far this removal is looking pretty uncontroversial :eyes:

I’ll give it more time for others to chime in, but right now my plan is to open the deprecation PR and add this PR to the 25.x milestone so we don’t forget about it in a year’s time.

https://github.com/llvm/llvm-project/pull/185879