[clang] [clang-tools-extra] [Clang] Add __type_list_dedup builtin to deduplicate types in template arguments (PR #106730)

[Ilya Biryukov via cfe-commits]

ilya-biryukov wrote:

I still need to add code that preserves source locations for template arguments and tests for it, but otherwise this is ready for review and I would like to get some initial feedback.

The RFC did not get any comments so far, but also happy to discuss the general design there.

https://github.com/llvm/llvm-project/pull/106730