[llvm] [LLVM] Create `lf_alias` nodes for `typedef` and `using` (PR #153936)

[Alexandre Ganea via llvm-commits]

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aganea wrote:

As @Michael137 says above, the whole test should be self-enclosed. The test, the inputs and the post-checks should all live in this file. Please look at past commits to understand how other LF_* records were implemented.

https://github.com/llvm/llvm-project/pull/153936