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

[Michael Buch via llvm-commits]

https://github.com/Michael137 commented:

On the surface seems simple enough. Don't know much about PDB internals though, so will defer approval to someone more familiar with it

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