[lldb] [llvm] [LLVM] [LLDB] Emit and handle `lf_alias` nodes (PR #152484)

[David Blaikie via llvm-commits]

dwblaikie wrote:

(I'm not particularly up on the details of PDB - but this patch should land, if/when it lands, in a few parts (& maybe should be separate pull requests) - the LLVM side of things, for instance, could be separated from the LLDB parts at least, I think)

https://github.com/llvm/llvm-project/pull/152484