[clang-tools-extra] [Clang-Tidy] Add google-runtime-float Clang-Tidy check (PR #156763)

[JJ Marr via cfe-commits]

jj-marr wrote:

> LGTM, minus open question with `portability`, but it doesn't block for me

Google's style guide only allows `float` and `double`, `portability-avoid-platform-specific-fundamental-types` recommends against them in favour of `float32_t` and `float64_t`. The advice is contradictory to Google's right now, although stdfloat was only introduced in C++23 so perhaps it'll change.

https://github.com/llvm/llvm-project/pull/156763