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

[Alexandre Ganea via llvm-commits]

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aganea wrote:

@Walnut356 We usually cover "can LLVM read the node" and "can LLVM generate the node" at once. There are some rare cases, such as `.pch.obj` which clang-cl doesn't generate, but can read, which require binaries generated by `cl.exe`. In most other cases, we can just use `yaml2pdb` or `yaml2obj` or vice-versa, `obj2yaml` or `llvm-pdbutil` for dumping the output of an existing `.obj/.pdb`. `llvm-readobj` also is able to dump some Codeview debug info.

An example of this: https://github.com/llvm/llvm-project/blob/main/llvm/test/DebugInfo/PDB/obj-globalhash.test

Another example which uses `llvm-readobj` here: https://github.com/llvm/llvm-project/blob/main/llvm/test/DebugInfo/COFF/lambda.ll

There might be some legacy binaries lying around but ideally if LLVM can generate the `LF_` record, we can use the tooling above and shouldn't be adding binaries to the repo.

As for location, the tests should go in https://github.com/llvm/llvm-project/tree/main/llvm/test/DebugInfo

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