[clang-tools-extra] [clang-tidy] Add portability-avoid-platform-specific-fundamental-types (PR #146970)

[JJ Marr via cfe-commits]

jj-marr wrote:

> Please remove unnecessary comments that tell the same as code itself, speaking mostly about comments in `registerMatchers`. They mostly don't give any more information that matchers themselves.

To be honest, this is because I coded 98% of this with AI (except for the `.rst` documentation text which I mostly wrote myself). I am still getting used to stripping out useless comments and also how `llvm`/compilers in general work.

https://github.com/llvm/llvm-project/pull/146970