[clang-tools-extra] [clang-tidy] Add performance-redundant-lookup check (PR #125420)

[Balazs Benics via cfe-commits]

steakhal wrote:

I think this case would be caught by the static analyzer based implementation.

There the loop would be unrolled about 3-4 times, so the checker should get to see the redundant lookups.

I'll check if my assessment is correct.

But I decided that the complexity does not worth the CSA based solution compared to the AST based.

Both has their ups and downs.

https://github.com/llvm/llvm-project/pull/125420