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

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Walnut356 wrote:

Ah, yeah. Those test failures are from LLDB's native PDB parser, which doesn't (currently) understand `lf_alias` nodes at all. I had a PR that implemented both the LLVM node creation and the LLDB node processing: https://github.com/llvm/llvm-project/pull/152484, but was told to split it between two PRs. 

I can go ahead and add the LLDB handling into this one though

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