[llvm] [ADT] Add TrieRawHashMap (PR #69528)

[Steven Wu via llvm-commits]

cachemeifyoucan wrote:

> Per https://llvm.org/docs/GitHub.html#updating-pull-requests it'd be helpful to, "When updating a pull request, you should push additional “fix up” commits to your branch instead of force pushing. This makes it easier for GitHub to track the context of previous review comments. Consider using the [built-in support for fixups](https://git-scm.com/docs/git-commit#Documentation/git-commit.txt---fixupamendrewordltcommitgt) in git."

Oops, I didn't realize we push out an official guideline already. Definitely will do that in the future. At the meantime, let me see if the review history can snap back to the code if I restore the branch to old stage and add fixup commit.

https://github.com/llvm/llvm-project/pull/69528