[clang-tools-extra] [clang-tidy] Add llvm-analyzer-unused-program-state-ref check (PR #211647)

[Balázs Benics via cfe-commits]

steakhal wrote:

> I think https://clang.llvm.org/docs/AttributeReference.html#warn-unused is what you need.

This is great! Closing in favour of https://github.com/llvm/llvm-project/pull/211795

https://github.com/llvm/llvm-project/pull/211647