[clang] [llvm] [clang-format] Add CI check confirming ClangFormatStyleOptions.rst is up-to-date. (PR #111513)

[Iuri Chaer via llvm-commits]

ichaer wrote:

> It would be nice if I didn't have to run step 4 manually.

Got it! So ideally we'd move `clang-format-style-options` lower down the stack, to a target shared between `clang-format` and `FormatTests`.

I've made it a dependency of the `clangFormat` library, let me know what you think :).

https://github.com/llvm/llvm-project/pull/111513